Method and system for selective application of cellular-PBX integration service

ABSTRACT

A method and system for selectively applying a cellular-PBX integration service. When a radio access network (RAN) receives a call request seeking to set up a call for a cellular wireless communication device (WCD) that is operating in the coverage area of the RAN, a determination is made as to whether the WCD is currently checked-into a cellular-PBX integration service. A service control point (SCP), for instance, may make the determination. If the determination is that the WCD is currently checked-in, then the call is set up to an IP PBX server that services the WCD, and the IP PBX server may then handle the call as it would handle a call placed to any IP PBX extension. Further, differential billing can be applied, charging an enterprise billing-account for the call if the WCD is checked-in, and charging a WCD billing-account for the call if the WCD is not checked-in.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 11/135,875,filed May 24, 2005, which is a continuation-in-part of co-owned U.S.patent application Ser. No. 10/902,323, filed Jul. 29, 2004, theentirety of both of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to telecommunications and, moreparticularly, to cellular wireless communications and private branchexchange communications.

BACKGROUND

Private branch exchange (PBX) systems are well known in the art. In atypical arrangement, an enterprise will operate a PBX server thatinterfaces between each of the telephone stations in the enterprise anda local telephone company central office of the public switchedtelephone network (PSTN). Conventionally, each telephone station willhave an assigned PBX extension number, and some of the stations may alsohave direct inbound dial (DID) numbers for receiving calls directly fromthe PSTN. The PBX server may then provide its stations with many usefulfeatures, such as the ability to dial by extension, the ability totransfer calls, the ability to establish conference calls, and theability to interact with an enterprise voice mail service.

Traditional PBX servers connect with each of their served telephonestations by a respective physical telephone line, which can beinefficient and difficult to manage. Recent improvements inVoice-over-IP communications have made possible an improved form of PBXserver, known generally as an IP PBX server. Typically, an IP PBX serversits as a node on an enterprise's computer network (e.g., LAN), and eachof the enterprise telephone stations in turn sits as a respective nodeon the computer network as well. Signaling and bearer communicationsbetween the telephone stations and the IP PBX server then traverse thecomputer network as IP communications. Like a conventional PBX server,the IP PBX server may be coupled to a telephone company central office,so that the enterprise telephone stations can place and receive callsvia the PSTN.

An enterprise IP PBX system provides great convenience for users ofdesktop telephone stations at the enterprise. Increasingly, however,people are often working from home or otherwise on the road, rather thanat the office. As such, people frequently use cellular wirelesscommunication devices (WCDs), such as cell phones, rather than theirdesktop enterprise telephone stations. WCDs place and receive callsthrough cellular radio access networks, rather than through an IP PBXsystem. Thus, when on the road, an enterprise worker would not benefitfrom the features of the enterprise IP PBX system (other than by dialinginto the IP PBX system through a DID telephone number.)

SUMMARY

As disclosed herein, an IP PBX system that serves enterprise telephonesvia a landline IP network connection can be expanded to serve cellularwireless communication devices (WCD) via a cellular wireless carrier'sradio access network (RAN). To do so, a signaling and bearer pathinfrastructure will be placed between the cellular carrier's RAN and theIP PBX system. Calls to and from the cellular WCD can then beselectively connected through the IP PBX system, so that the IP PBXsystem can control and manage the calls just as the IP PBX would controland manage calls involving other extensions on the IP PBX.

With this arrangement, a cellular WCD can thus become an IP PBX clientstation, i.e., an extension on an off-the-shelf IP PBX server. As such,in an ideal arrangement, the cellular WCD would seamlessly benefit frommany of the same IP PBX features that other more conventional IP PBXclient stations would enjoy. Further, the cellular WCD would seamlesslybenefit from these features anywhere within coverage of the cellularcarrier's network.

By way of example, the cellular WCD can have an assigned PBX extensionnumber and can thus receive inside-calls placed to that extension numberfrom other stations in the IP PBX system and place inside-calls to otherstations in the IP PBX system by dialing their extension numbers. Asanother example, the cellular WCD can ideally transfer an existing callto another extension in the IP PBX system and set up conference callswith other extensions in the IP PBX system. And as another example, thecellular WCD can ideally benefit from a voice mail system associatedwith the IP PBX system, so that unanswered calls to the cellular WCD canbe forwarded to the voice mail system, and a user of the cellular WCDcan readily access the voice mail system to listen to messages. Further,the cellular WCD can ideally dial IP PBX feature codes to access variousfeatures of the IP PBX system.

At the same time, the cellular WCD would ideally maintain a publicdirectory number and could thus receive outside calls placed to thatdirectory number and place outside calls from that directory number.Further, as a client device served by a cellular carrier, the cellularWCD would ideally benefit from another voice mail system associated withthe cellular carrier, so that unanswered calls to the cellular WCD couldalternatively be forwarded to the cellular carrier's voice mail system.And still similarly, the cellular WCD would ideally be able to dialfeature codes and invoke other features that are specific to thecellular carrier's system.

In accordance with exemplary embodiments described more fully below,still additional methods and systems can be provided in order control orlimit application of this cellular-PBX integration function. In onerespect, for instance, a user (e.g., end-user or system administrator)can be given the ability to selectively turn on or off the cellular-PBXintegration function for a given cellular WCD, either generally,according to a user-defined schedule, or on a per-call basis. In anotherrespect, location of the WCD can be used as a basis to determine whetherto apply the cellular-PBX integration function, such as by restrictingoperation of the cellular-PBX integration function to when the WCD is ina home zone or other designated location. In still another respect, anaccount-balance limitation can be imposed on application of thecellular-PBX integration function, such as by limiting a given WCD tousing the function for only a certain number of minutes per month forinstance.

In yet another respect, a method and system can be applied to determinedynamically which of cellular WCD's voice mail systems should be appliedin a given instance, that is, whether to apply the WCD's “enterprise”(PBX-based) voice mail system and when to apply the user's the WCD's“personal” (cellular-carrier based) voice mail system. In this regard,an interactive voice response unit (IVRU) could prompt a caller in realtime to select which of these or other voice mail systems should handlean unanswered or busy call. Alternatively, calls could be routed to theWCD's enterprise voice mail system when the cellular-PBX integrationfunction is turned on for the WCD and to the WCD's personal voice mailsystem when the cellular-PBX integration function is turned off for theWCD.

Still further, in another respect, a method and system can be applied tofacilitate differential billing, so as to cause a cellular carrier tobill cellular-PBX integration calls to an enterprise while billingtraditional cellular calls to the WCD account holder.

These and other aspects, advantages, and alternatives will becomeapparent to those of ordinary skill in the art by reading the followingdetailed description, with reference where appropriate to theaccompanying drawings. Further, it should be understood that thedescriptions in the foregoing summary and elsewhere herein are intendedto be examples only rather than necessary limitations of the claimedinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting a cellular wireless communicationsystem.

FIG. 2 is a block diagram depicting a basic IP PBX system.

FIG. 3 is a block diagram depicting exemplary signaling and bearer pathinfrastructure between a carrier's RAN and an IP PBX server.

FIG. 4 is a block diagram depicting a network arrangement providing theexemplary signaling and bearer path infrastructure between the RAN andthe IP PBX server.

FIG. 5 is a block diagram depicting cellular-PBX integration set tosupport multiple IP PBX servers.

FIG. 6 is a block diagram depicting a master IP PBX server arrangement.

FIGS. 7-13 are flow charts depicting functions that can be carried inaccordance with exemplary enhancements of cellular-PBX integrationservice.

DETAILED DESCRIPTION

1. Base Network Architecture

To provide some perspective for the embodiments described below, FIG. 1is a block diagram depicting the arrangement of a basic cellularwireless communication system, and FIG. 2 is a block diagram depictingthe arrangement of a basic IP PBX system. It should be understood, ofcourse, that these are merely examples and that other arrangements ofcellular wireless systems and IP PBX systems are equally possible.

a. Cellular Wireless Communication System

As shown first in FIG. 1, a typical cellular wireless communicationsystem includes at its core a radio access network (RAN) 12, whichserves one or more wireless communication devices, such as WCD 14 forinstance. The RAN 12 includes a base transceiver station (BTS) 16, whichradiates to define an air interface 18 through which WCD 14 cancommunicate, and a base station controller (BSC) 20 that manages airinterface communications. Further, the RAN includes a mobile switchingcenter (MSC) 22 or other switching point that provides connectivity withthe PSTN 24.

MSC 22 is coupled with an out of band signaling network, represented inFIG. 1 by signal transfer point (STP) 26, through which MSC 22 canengage in signaling to set up calls, to obtain call processing guidance,to acquire profile logic for the WCDs that it serves. To set up a callover the PSTN, for instance, MSC 22 may conventionally engage in SS7(Integrated Services Digital Network (ISDN) User Part, or “ISUP”)signaling via STP 26 with a remote switching point (SP) 28 that serves aremote telephone device 30. To obtain call processing guidance, MSC 22may send a query message via STP 26 to a service control point (SCP) 32or other entity and may then receive a call-handling directive from thatentity. To acquire profile logic for a served WCD, MSC 22 may receive aservice profile for the WCD from a home location register (HLR) 34, viathe STP 26, and MSC 22 may store that profile in a visitor locationregister (VLR) 36 for reference.

With this basic arrangement, WCD 14 can place and receive calls overPSTN 24. For instance, to place a call to remote telephone device 30,WCD 14 may send a call origination message over an access channel on airinterface 18 to RAN 12, which would provide MSC 22 with dialed digitsrepresenting the telephone number of device 30.

Pursuant to logic defined generally for the MSC or logic definedspecifically by the WCD's service profile, MSC 22 may then pause callprocessing and query up to SCP 32 to obtain call processing guidance.For instance, MSC 22 may send an IS-41 “Origination Request” (ORREQ)message via STP 26 to SCP 32, providing SCP 32 with the calling andcalled telephone numbers and any other pertinent information. SCP 32 maythen apply service logic to decide how the call should be handled andsend a call handling directive via STP 26 to MSC 22. And MSC may thencarry out that directive.

In a normal case (absent some contrary directive), MSC 22 would directBSC 20 to assign an air interface traffic channel over which WCD 14 cancommunicate. Further, MSC 22 would work to set up a call path to thecalled device 30, typically by engaging in SS7 ISUP signaling. Forinstance, MSC 22 may first send an ISUP “Initial Address Message” (IAM)via STP 26 to SP 28. SP 28 would then reserve a trunk for the call andsend an ISUP “Address Complete Message” (ACM) via STP 26 to MSC 22,indicating the port/trunk reserved. MSC 22 would then connect the callthrough to that trunk and send a ringing tone to the calling WCD 14.When the called party answers (goes off hook), SP 28 would in turn sendan ISUP “Answer Message” (ANM) to the MSC to complete call setup, andthe call would then commence.

Similarly, if MSC 22 receives a signaling message (such as an IAMmessage) from SP 28 seeking to set up a call to WCD 14 from device 30,MSC 22 may query SCP 32 for call processing guidance, and, assuming thecall should go through, MSC 22 may page WCD 14 over a paging channel onair interface 18 and may direct BSC 20 to assign a traffic channelthrough which WCD 14 can communicate. When WCD 14 answers the call, MSC22 may signal back to SP 26 to complete setup of a call path throughPSTN 24, so that the call can commence.

As further shown in FIG. 1, MSC 22 may be coupled by a voice trunk witha voice mail server (VMS) 38. In traditional practice, when MSC 22receives a request to set up a call to WCD 14, if the call isunanswered, busy, or otherwise not connectable, MSC 22 may route thecall to VMS 38 for handling in a manner well known in the art.

In addition, FIG. 1 depicts another feature commonly found in mostcellular wireless systems, namely, a mobile positioning center (MPC) 40.MPC 40, which is conventionally coupled with STP 26, functions todetermine the location of a WCD and to store and report that location,in order to facilitate various location-based services such as 9-1-1call-handling for instance. In practice, MPC 40 receives a request for aWCD's location and then responsively invoke a process well known in theart to determine the location (if not already known). For instance, MPC40 or an associated position determining entity may engage in signaling(via MSC 22) with the WCD 14, to obtain a granular GPS location reading.Alternatively, MPC 40 may simply engage in signaling with MSC 22 or HLR18 to determine the cell or cell sector in which the WCD is currentlyoperating (or was last registered). MPC 40 can determine a WCD'slocation in other ways as well. As shown, MPC 40 may be coupled with apacket-switched network 52, through which MPC 40 may receive and respondto location-requests.

b. IP PBX System

As shown next in FIG. 2, a typical IP PBX system includes at its core anIP PBX server 50, such as one manufactured by Avaya Inc. (e.g., the“Communications Manager” platform), Cisco Systems, Inc. (e.g., the“Avid” platform), Nortel Networks, Ltd. (e.g., the “MCS” platform), or3Com Corporation (e.g., the “NBX” platform), for instance. The IP PBXserver 50 normally sits as a node on a packet-switched network 52, whichtypically comprises an enterprise local area network (LAN) but couldtake other forms as well.

Communicatively linked with the packet-switched network 52 are thenmultiple end-user telephone stations, represented in FIG. 2 by devices54, 56, 58, each of which may have an extension defined by IP PBX server50. Each of these telephone stations may be a voice over IP (VoIP)telephony device (such as an IP telephone, IP fax machine, multi-mediacomputer, media terminal adapter, analog terminal adapter, or otherdevice) that is capable of engaging in packetized bearer and signalingcommunication with the IP PBX server 50 so as to communicate real timemedia such as voice, video or audio, or other data or information (e.g.,fax or modem data) that is normally carried over a telephone line. Alsolinked with the packet-switched network is an enterprise voice mailserver 60. The enterprise voice mail server 60 may be integrated as afunction of the IP PBX server 50 or, as shown, may exist as a separatecomponent.

IP PBX server 50 is coupled via one or more T1 lines, PRI lines, orother high capacity circuit link 62 with a local telephone companycentral office (CO) 64, which provides connectivity with the PSTN 66. Ina usual arrangement, the link between IP PBX server 50 and CO 64 maycarry multiple subscriber (local loop) telephone lines, each providing adirect dial line for the enterprise. Through this link and the IP PBXserver 50, the enterprise telephone stations can place and receive callsover the PSTN 66.

IP PBX server 50 normally includes or has access to configuration data(not shown) for each of the enterprise telephone stations that itserves. For each station, the configuration data defines a PBX extensionand other service parameters and preferences, such as preferences tohave unanswered calls forwarded to the enterprise voice mail server 60,and the like. Further, the configuration data may correlate DID numberswith certain stations, so as to allow PSTN calls to be placed directlyto those stations (rather than being placed to a main IP PBX number andfrom there being transferred to the stations).

One or more computer terminals sitting on the network 52 or coupleddirectly with IP PBX server may be used to provision the configurationdata for the various telephone stations. For instance, an administratorterminal 72 may run a provisioning program or provide access to aweb-based provisioning program, through which an administrator can setup and manage IP PBX configuration parameters for the various telephonestations.

In practice, the enterprise telephone devices will engage in signalingcommunication with the IP PBX server 50 using a proprietary or standardsignaling protocol to set up and manage calls. By way of example,suitable protocols include H.323 and Session Initiation Protocol (SIP),each of which are well known. Using SIP, for instance, an enterprisetelephone station could send an IP-based SIP “INVITE” message to the IPPBX server 50, in an effort to set up a call to another extension on theIP PBX server or a call to an outside telephone number.

If the call is an inside call, the IP PBX server 50 may then send a SIPINVITE in turn to the called station, to cause the station to ring. Whenthe called station answers, the called station may respond to the IP PBXserver 50 with a SIP “200 OK” message, and the IP PBX server 50 may inturn respond to the calling station with a SIP 200 OK message. Afterfurther SIP signaling, a VoIP (e.g., Real-time Transport Protocol) voicesession would be set up between the calling and called stations, so thatusers of the stations can communicate with each other. If the call is anoutside call, on the other hand, the IP PBX server 50 may forward (orallow pass-through of) the digits dialed by the calling station, vialink 62, to CO 64, and CO 64 may set up the call over PSTN 66 to thecalled party.

During an ongoing call that an enterprise telephone station establishesthrough IP PBX server 50, a signaling path remains between theenterprise telephone station and the IP PBX server 50. Further, in somecases (such as with outside calls), the bearer path of the call alsopasses through the IP PBX server 50. Consequently, during an ongoingcall, a user of the enterprise telephone station can invoke IP PBXfunctions, such as call transfer, conference calling, or the like.

As noted above, an IP PBX server 50 will sit as a node on one or more IPnetworks. Typically, for instance, the IP PBX server will sit as a nodeon an enterprise LAN and will be located physically at the enterprisepremises. In that case, the enterprise will typically buy or lease theIP PBX server 50 and will manage operation of the server. Unfortunately,however, this can be a burden for the enterprise.

In an alternative arrangement, the IP PBX server 50 can be physicallyhosted and managed by a telecom carrier or other entity outside of theenterprise and can be coupled by a packet-data connection with theenterprise network. That way, the outside entity can provide IP PBXservice for the enterprise, while relieving the enterprise of much ofthe responsibility for acquiring and managing an IP PBX server of itsown. In this alternative arrangement, the network cloud 52 shown in FIG.2 between the IP PBX server and the enterprise telephone stations mayinclude both the enterprise network and one or more external IP networksor other communication links, such as the Internet and a telecomcarrier's core packet-data network for instance.

In this alternative arrangement as well, the IP PBX server 50 maymaintain configuration data for each of the enterprise telephonestations and may engage in signaling communication (e.g., SIP or H.323)with the enterprise telephone stations to set up and manage both insideand outside calls. Further, an administrator terminal 72 located at theenterprise network or elsewhere could be arranged to provisionconfiguration data on the IP PBX server 50.

2. Cellular-PBX Integration

In accordance with the exemplary embodiment, an IP PBX system thatserves enterprise telephone stations will be expanded to serve cellularwireless communication devices via a conventional cellular RAN. Toaccomplish this, as noted above, a signaling and bearer pathinfrastructure will be placed between the cellular carrier's RAN and theIP PBX system. Calls to and from cellular WCDs will then be connectedthrough the IP PBX system (or at least with signaling passing throughthe IP PBX system), so that the IP PBX system can control and manage thecalls just as the IP PBX system would control and manage calls involvingother extensions on the IP PBX. FIGS. 3 and 4 are simplified blockdiagram depicting an example network arrangement for integrating an IPPBX system and a cellular wireless communication system in this manner.It should be understood, however, that other arrangements are possibleas well.

As shown in FIG. 3, an exemplary signaling and bearer pathinfrastructure between a cellular carrier's RAN 12 and an IP PBX server50 includes a media gateway system 74 and a call session controlfunction (CSCF) 76.

In a preferred embodiment, the media gateway system 74 includes a mediagateway (MGW) 78, which converts between bearer data formats used in thePSTN (such as a pulse code modulated (PCM) format or another timedivision multiplex (TDM) format) and bearer data formats used forIP-based communication (such as a Real-time Transport Protocol (RTP)format). Further, the media gateway system 74 includes a media gatewaycontroller (MGC) 80, which converts between signaling formats used toset up and manage calls in the PSTN (such as SS7 signaling) andsignaling formats used to set up and manage calls over IP (such as SIPor H.323). MGW 78 and MGC 80 can be integrated together or can bedistributed, and they can be programmed to communicate with each otherthrough an accepted gateway control protocol such as H.248 or MediaGateway Control Protocol (MGCP) for instance. Media gateway system 74can take other forms as well.

Call session control function (CSCF) 76 serves as a trigger point toinvoke various policy logic when setting up a communication in theintegrated cellular-PBX system. As shown, CSCF 76 preferably includes orhas access to a subscriber profile store such as a home subscriberserver (HSS) 82, which contains profile data for subscribers to theinventive service. CSCF 76 further includes or has a communication linkwith various policy servers 84, which contain policy logic fordetermining how to handle particular communication setup requests andthe like. CSCF 76 is then coupled with IP PBX server 50, so as tofacilitate signaling with the IP PBX server. Further, CSCF 76 is coupledwith one or more voice mail servers 86, so as to facilitate signalingwith the voice mail server(s).

MGC 80 functions to pass session setup and control signaling between STP26 (e.g., as SS7 signaling) and CSCF 76 (e.g., as SIP signaling). MGW78, in coordination with MGC 80, functions to pass bearer trafficbetween MSC 22 (e.g., as PCM data) and IP PBX server 50 (e.g., as RTPdata) or voice mail server(s) (also e.g., as RTP data).

FIG. 4 next depicts more specifically a preferred network arrangementproviding the exemplary signaling and bearer path infrastructure betweenRAN 12 and IP PBX server 50. As shown in FIG. 4, one or morepacket-switched networks, cooperatively shown as network cloud 90, sitsbetween media gateway system 74 and IP PBX server 50. Sitting as nodeson network 90, in addition to the MGW 78, MGC 80, and IP PBX server 50,are CSCF 76, HSS 82, policy servers 84, and voice mail server(s) 86.Additionally sitting as nodes on the network 90 are MPC 40 to be usedfor location-determination, and an ENUM and/or DNS server 92 to be usedto facilitate routing of IP traffic.

In the arrangement shown, policy servers 84 include apersonal-enterprise (PE) policy server 94, a location policy server 96,a voice mail policy server 98, and an account balance policy server 100.These policy servers can be embodied as discrete server cards and canall be housed together in a chassis, such as an IBM Blade Server, forinstance, each with its own IP address. Alternatively, the policyservers could be embodied as server functions in the form of programlogic modules all executable by one or more common processors.Preferably, CSCF 76 is programmed to reference, query, and/or routesignaling messages (such as SIP messages) through these or other policyservers.

With the arrangement as illustrated in FIGS. 3 and 4, a bearercommunication path extends between MSC 22 and IP PBX server 50 via MGW78. In particular, a circuit link such as a PSTN voice trunk extendsbetween MSC 22 and MGW 78, and a packet-link such as an Ethernet line orpacket-switched network extends between MGW 78 and IP PBX server 50.Bearer telephony traffic may therefore flow between MSC 22 and MGW 78 asPCM data or in any other form(s) in which bearer telephony traffic canflow between MSC 22 and another switching point on the PSTN. And bearertelephony traffic may flow between MGW 78 and IP PBX server 50 as RTP/IPdata or in any other form(s) in which bearer telephony traffic can flowover a packet-switched network. MGW 78 would then operate to convertbetween these forms of bearer traffic so as to allow end-to-end bearercommunication between the MSC 22 and the IP PBX server 50.

Further, a signaling path extends between MSC 22 and IP PBX server 50via MGC 80 and CSCF 76. In particular, an SS7 signaling path extendsbetween MSC 22 and MGC 80 via STP 26, just as an SS7 signaling pathwould normally extend between MSC 22 and another PSTN switching pointvia STP 26. An IP-based signaling path such as an Ethernet link orpacket-switched network extends between MGC 80 and CSCF 76. Similarly,an IP-based signaling path also extends between CSCF 76 and IP PBXserver 50. SS7 signaling traffic may then flow between MSC 22 and MGC80, and IP-based signaling traffic, such as SIP or H.323 traffic, mayflow between MGC 80 and IP PBX server 50 via CSCF 76. MGC 80 wouldoperate to convert between these forms of signaling traffic so as toallow end-to-end signaling communication between MSC 22 and IP PBXserver 50.

As further shown in FIG. 3, IP PBX server 50 may include or be connectedwith a media server (or, more generally, a media server function), tofacilitate engaging in RTP or other bearer communication with MSC 22,via MGW 78. For instance, if the IP PBX server is an Avaya S8700 PBXserver, the media server could be an Avaya G600 media server. The IP PBXserver and media server can be separately coupled with the CSCF 76, orthey may have a common packet-data link (e.g., a common network orrouter connection) with the CSCF 76.

In a preferred embodiment, the wireless carrier that owns and operatesRAN 12 will position MGW 78 at the same physical site as the MSC 22, soas to facilitate easy shunting of calls between the MSC 22 and the MGW78. (As presently envisioned, a carrier that operates many MSCs mayposition a respective MGW 78 at each MSC site.) Further, the carrier mayposition the MGC 80 as a node on its core signaling network, so as tofacilitate SS7 signaling between the MSC 22 and the MGC 80, and thecarrier may position MGC 80, CSCF 76, and other entities on a corepacket network, to facilitate packet-based signaling between thoseentities.

At each MSC site, for instance, the carrier may connect the MGW 78 by aninter-machine trunk (IMT) or primary rate interface (PRI) line to aswitch port of MSC 22. Further, the carrier may couple the MGW 78 with apacket-data connection (e.g., Ethernet link, carrier's core packetnetwork, Internet, etc.) to the MGC 80, to facilitate H.248, MGCP orother signaling between the MGW 78 and the MGC 80. Further, the carriermay couple the MGC 80 with a similar packet-data connection to the CSCF76, and the CSCF 76 with a similar packet-data connection to the IP PBXserver 50, to facilitate IP-based signaling communication between theMGC 80 and the IP PBX server 50. In addition, the carrier may couple theMGW 78 with a packet-data connection to the IP PBX server 50 (and/ormedia server), to facilitate bearer communication between the MGW 78 andthe IP PBX server 50.

As noted above, an IP PBX server 50 can sit on the enterprise network orcan be hosted outside of the enterprise. (As will be described below, anIP PBX system 50 can alternatively comprise both an IP PBX server on theenterprise network and an IP PBX server outside of the enterprisenetwork.) In the scenario where the IP PBX server 50 resides on theenterprise network, the packet-data connection between the MGW 78 andthe IP PBX server 50 could include the carrier's core packet network andthe Internet or other link, and the packet-data connection between theCSCF 76 and the IP PBX server 50 could similarly include the carrier'score packet network and the Internet or other link. Further, theenterprise network would provide packet-data connectivity between the IPPBX server 50 and the enterprise telephone stations.

In the scenario where the IP PBX server 50 is hosted outside of theenterprise network, such as on the carrier's core packet network forinstance, the packet-data connections between the MGW 78 and the IP PBXserver 50 and between the CSCF 76 and the IP PBX server 50 couldsimilarly be the carrier's core network or could take some other form.Further, the carrier would couple IP PBX server 50 with a packet-dataconnection (including, for instance, the carrier's core network and theInternet) to the enterprise network, so that the IP PBX server 50 canengage in IP-based signaling and bearer communication with theenterprise telephone stations and/or other entities on the enterprisenetwork.

Various entities shown in FIGS. 3 and 4 will preferably be configuredwith logic to facilitate operation of the invention. By way of example,each entity may include or have access to one or more processors (e.g.,general purpose and/or special purpose processors), one or more datastorage elements (e.g., volatile and/or non-volatile storage), and oneor more communication interfaces (e.g., Ethernet network interfacemodules, or other interfaces) to facilitate communication over thevarious links shown. The data storage of each entity may containreference data and/or program instructions (e.g., machine languageinstructions) executable by a processor (i.e., one or more processors)to carry out various functions described herein. Alternatively, theentities can include hardware or firmware, or any combination ofhardware, firmware, and/or software, designed to carry out thefunctions.

HLR 34, for instance, may include or have access to profile records orother service logic for subscribers, such as a profile record for WCD 14for instance. The profile record or other service logic may definewireless intelligent network (WIN) trigger logic for causing MSC 22 toquery SCP 32 for call processing guidance when MSC 22 is faced with arequest to set up a call for (i.e., to or from) WCD 14. Conventionally,HLR 34 would send such logic to MSC 22 (e.g., in an IS-41 registrationnotification response or qualification directive) for storage in VLR 36,when WCD 14 registers in the service area of MSC 22, when the logic inHLR 34 gets updated, or at other times.

SCP 32 may similarly include or have access to a profile record or otherservice logic for WCD 14. The profile record may include an indicationof whether the WCD subscribes to cellular-PBX integration service, andwhether the service is currently active or inactive for the WCD, thatis, whether or not the service is to be applied for the WCD. The profilerecord or other service logic in SCP 32 may thus indicate that, when MSC22 is faced with a request to set up a call for WCD 14, MSC 22 shouldset up the call to media gateway system 74, i.e., by engaging in SS7signaling with MGC 80. As will be explained below, the logic in SCP 32may also indicate that, if a call to WCD 14 has already been routed toIP PBX server 50 and back to MSC 22, the call should not again be routedto IP PBX server 50 (to avoid endless looping).

HSS 82 may similarly include or have access to a profile record or otherservice logic for WCD 14. This profile record may similarly include anindication of whether the WCD subscribes to cellular-PBX integrationservice, and whether the service is currently active or inactive for theWCD. The profile record or other service logic in the HSS 82 mayindicate that, when CSCF 76 is faced with a request to set up a call fora WCD 14, the CSCF should route call setup signaling to one or moreentities, such as to one or more of the policy servers 84 for instance.

For instance, based on a telephone number URI in the “To” or “From”field of a SIP INVITE message, the CSCF 76 may obtain from HSS 82 aparticular domain name, such as “pe-policy.com”, “location-policy.com”,“voicemail-policy.com” or “account-balance-policy.com” and may then dipinto DNS server 92 to resolve that domain name into a routable IPaddress and then send the INVITE (or a corresponding INVITE) to that IPaddress. Further, upon receipt of such a signaling message, the policyserver itself may dip into the HSS 82 to obtain service logic parametersfor the calling party or called party. The policy server may thenfurther modify or reform the signaling message and pass it back or alongto CSCF 76, which may then carry out a designated service policy.

IP PBX server 50, as well, may include or have access to profile data orservice logic for WCD 14. In a preferred embodiment, the profile data orservice logic of IP PBX server 50 would define configuration data forWCD 14, which would assign an IP PBX extension number to the WCD 14, andwhich would correlate the extension number with the directory number(e.g., mobile directory number) of the WCD 14. As with the configurationdata for more conventional IP PBX extensions (e.g. traditionalenterprise telephone stations), the configuration data for WCD 14 maydefine service preferences, such as whether to forward calls to voicemail and the like. Thus, when IP PBX server 50 is faced with a requestto set up a call to or from WCD 14, IP PBX server 50 can apply thoseservice preferences or other logic as it would for a call being placedto or from any other one of its extensions.

The configuration data for WCD 14 may also correlate the extension ofWCD 14 with another extension on IP PBX server 50. For instance, if anenterprise user normally uses a particular desk phone when at work (onthe enterprise network) but uses WCD 14 when on the road, theconfiguration data for WCD 14 can correlate the extension of WCD 14 withthe extension of the user's desk phone. That way, when IP PBX server 50is faced with a request to set up a call to or from WCD 14, IP PBXserver 50 can programmatically set up the call to both WCD 14 and theuser's desk phone extension, either simultaneously ringing both phones(and connecting with the one that answers first) or sequentially ringingboth phones.

The configuration data for WCD 14 will be marked or have acharacteristic of some kind that indicates IP PBX server 50 shouldhandle calls for WCD 14 in a special way. For instance, theconfiguration data could be flagged (e.g., by the mere existence of amobile directory number in the configuration data) to indicate that theWCD 14 is a WCD, and could indicate a network address of the CSCF 76 towhich call setup signaling can be sent for WCD 14. (This canadvantageously allow a given IP PBX server to extend its service to WCDsserved by more than one wireless carrier, or through more than one mediagateway system.)

Thus, for instance, when the IP PBX server 50 is faced with a request toconnect a call to WCD 14, the IP PBX server 50 may determine based onthe WCD's configuration data that the IP PBX server 50 shouldsimultaneously set up the call to both the WCD 14 (via media gatewaysystem 74 and RAN 12) and to the WCD user's desk phone on the enterprisenetwork. As another example, when the IP PBX server 50 is faced with arequest to connect a call from the WCD 14, the IP PBX server 50 maydetermine based on the WCD's configuration data how to handle the calland may handle the call accordingly.

A provisioning system may be in place to centrally configure HLR 34, SCP32, HSS 82, CSCF 76, and IP PBX server 50 (as well as any other desiredentities) with service settings to facilitate operation of theinvention. The provisioning system can include a computer server (suchas an “Actiview” server) that sits on the carrier's core network andthat is programmed to communicate directly or through one or more otherservice provisioning interfaces (e.g., service management systems,enhanced service managers, etc.) with the various entities to beprovisioned. In a preferred embodiment, the provisioning server wouldengage in industry standard CORBA signaling to convey provisioningupdates to the various entities. Further, the administrator terminal 72or another user terminal can be communicatively linked with theprovisioning system (e.g., through a web interface) so as to allow anadministrator or other user to configure IP PBX services for WCD 14.

The exemplary arrangement generally depicted in FIGS. 3 and 4 can beexpanded to support multiple IP PBX servers, so that multiple IP PBXsystems can serve cellular WCDs via a common cellular carrier. Toaccomplish this in a preferred embodiment, profile data in HSS 82 orelsewhere can correlate each of a plurality of WCDs with a respective IPPBX server that serves the WCD (i.e., the IP PBX server on which the WCDis an extension). When the CSCF 76 or another entity (such as one of thepolicy servers 84) is faced with a request to set up a call to or from agiven WCD, the CSCF or other entity may then programmatically referencethe correlation data to determine which IP PBX server serves that WCD,and the CSCF or other entity may then engage in signaling with that IPPBX server in order to set up the call to or through the IP PBX server.

FIG. 5 depicts an example arrangement for carrying out this function. Asshown, the example arrangement includes several WCDs 101, 102, 103 andseveral IP PBX servers 105, 106, 107, with all of the IP PBX serversbeing coupled with a packet-data network that provides connectivity withCSCF 76, MGW 78, MGC 80, HSS 82, and policy servers 84. Each IP PBXserver, in turn, is shown coupled by a packet-data network with aplurality of enterprise telephone stations. For instance, each IP PBXserver may reside on a respective enterprise network, and eachenterprise network may have its own respective set of enterprisetelephone stations that are extensions on its IP PBX server.Alternatively, each IP PBX server may reside in a carrier's core networkand can function as a host IP PBX server for one or more enterprisenetworks, coupled by packet-data links with the enterprise networks thatthey serve. Still alternatively, some of the IP PBX servers may resideon enterprise networks and others may be host IP PBX servers that resideon a carrier's network or elsewhere.

As further shown in FIG. 5, HSS 82 includes or has access to correlationdata 112, which correlates WCDs with IP PBX servers. As shown, forinstance, the correlation data may take the form of a table of data, inwhich each record has a WCD identifier field and an IP PBX serveridentifier field. Each WCD identifier can be a WCD directory number(telephone number), a WCD serial number (e.g., ESN), a SIP address, anetwork access identifier, or some other identifier. Each IP PBX sereridentifier can be a domain name, a SIP address, an IP address, a networkaccess identifier, or some other identifier that can be used as a basisto route IP-based call setup signaling messages to the IP PBX server. Ina preferred embodiment, this data would be provisioned in HSS 82 by aprovisioning system such as that described above.

Thus, for instance, when CSCF 76 receives a signaling message seeking toset up an call placed to or from WCD 101, CSCF 76 may dip into HSS 82and determine by reference to correlation data 112 that IP PBX server105 serves the WCD, and so CSCF 76 may set up the call to IP PBX server105 for handling. On the other hand, when CSCF 76 receives a requestfrom MSC 22 seeking to set up a call placed to or from WCD 102, CSCF 76may dip into HSS 82 and determine by reference to correlation data 112that IP PBX server 106 serves the WCD, and so CSCF 76 may set up thecall to IP PBX server 106 for handling.

Alternatively but similarly, when a policy server such as the PE policyserver 94 receives a signaling message from CSCF 76 indicative of arequest to set up a call to or from WCD 101, the policy server may dipinto HSS 82 and determine by reference to correlation data 112 that IPPBX server 105 serves the WCD, and the policy server may responsivelyprovide CSCF 76 with a domain name of IP PBX server 105. CSCF 76 maythen set up the call to IP PBX server 105 for handling. And on the otherhand, when the policy server receives a signaling message from CSCF 76indicative of a request to set up a call to or from WCD 102, the policyserver may dip into HSS 82 and determine by reference to correlationdata 112 that IP PBX server 106 serves the WCD. The policy server maytherefore provide the CSCF with the domain name of IP PBX server 106,and the CSCF may set up the call to that IP PBX server for handling.

3. Example Basic Call Setup Signaling with Cellular-PBX Integration

Advantageously, while WCD 14 is being served by the cellular carrier'sRAN 12, WCD 14 can function as an extension of IP PBX server 50, so asto benefit from many or all of the same IP PBX services that enterprisetelephone stations 54, 56, 58 enjoy. Consequently, the enterprise canextend its off the shelf IP PBX system to serve not only traditional IPPBX telephone stations but also mobile WCDs such as WCD 14.

The following subsections describe various functions that can be carriedout in this manner, with reference to the network architecture of FIGS.3 and 4. It should be understood, however, that many variations fromthese functions are possible as well.

a. Originating Inside Calls

In a first scenario, assume that WCD 14 places a call to anotherextension on the enterprise network, by dialing the extension number. Todial an extension number from a conventional cellular WCD (e.g., cellphone), a user would enter the extension number and press “SEND” oranother key. An origination message will then pass over an air interfacefrom WCD 14 to MSC 22 in the carrier's RAN 12, providing the RAN with(i) the WCD's mobile directory number (MDN) and electronic serial number(ESN) or one or more other identifiers, and (ii) the dialed digits,which, in this case, would be the dialed PBX extension rather than afull directory number.

Upon receipt and processing of the origination message, the MSC may thenencounter a WIN trigger that points to the SCP. Thus, the MSC would sendan IS-41 “Origination Request” (ORREQ) message via the signaling networkto SCP 32, providing the SCP with the calling and called numbers. SCP 32may then refer to a subscriber profile store to determine that the WCDoriginating the call subscribes to cellular-PBX integration service.Thus, the SCP will send an Origination Request return result (orreq_rr)to MSC 22, providing the MSC with the routing number of MGC 80, so as tocause MSC 22 to set up the call to the media gateway system.

MSC 22 would then send an ISUP IAM call setup message via the signalingnetwork to MGC 80, providing the MGC with the calling and callednumbers, and indicating that the call is a WCD-originated call.(Existing call signaling protocols define a parameter that can be usedto indicate whether a call is a WCD-originated call (a call from a WCD)or a WCD-terminated call (a call to a WCD), for purposes of allowing acall processing entity to determine which party's profile to referencewhen setting up the call.) MGC 80 may then generate and send to CSCF 76a corresponding SIP INVITE message that specifies the called extensionas a telephone number URI in the “To” field, and that includes a headerparameter indicating this is a WCD-originated call.

In this instance, given that the call is WCD-originated, the CSCF 74 maythen dip into the correlation data 112 of HSS 82 to determine which hostIP PBX server serves the originating cellular WCD (e.g., based on itsMDN) and may obtain from correlation data 112 a domain name of theserving IP PBX server, such as IP PBX server 50. CSCF 76 may thenresponsively query DNS server 92 to resolve the domain name into an IPaddress of IP PBX server 50, and CSCF 76 may route the INVITE to that IPaddress.

SIP signaling may then proceed between the MGC 80 and IP PBX server 50,via the CSCF 76, to set up a voice/RTP call leg between MGW 78 and IPPBX server 50. At the same time, ISUP signaling would pass between MGC80 and MSC 22 to set up a circuit-switched (e.g., PCM) call leg betweenMSC 22 and the MGW 78.

At this point, IP PBX server 50 has thus received a signaling messageseeking to set up a call from WCD 14 to another IP PBX extension.Further, the IP PBX server 50 has a communication bearer path with WCD14, via the RTP leg, MGW 78, the circuit leg, MSC 22, and cellular airinterface 18. Thus, the IP PBX server 50 can apply the enterprise dialplan and thereby determine that this is a call to one of the enterpriseIP PBX extensions.

In response to the determination that this is a call to an enterprise IPPBX extension, the IP PBX server 50 may then set up the call with SIPand RTP to the enterprise telephone station having that extension. Forinstance, if the IP PBX server 50 sits on the enterprise network, the IPPBX server 50 may engage in SIP communication with the called station toset up an RTP call path between the IP PBX server 50 and the calledstation. Or if the IP PBX server 50 sits outside of the enterprisenetwork, on the carrier's core network for instance, the IP PBX servercan similarly engage in SIP communication with the called station, via apacket-data link with the enterprise network, and via the enterprisenetwork, to set up an RTP call path between the IP PBX server 50 and thecalled station.

Upon successful connection of the call between WCD 14 and the calledenterprise IP PBX extension, both the signaling and bearer paths wouldflow through the IP PBX server 50. Thus, the IP PBX server 50 canconveniently manage the call, providing IP PBX features such as calltransfer, conference calling, and the like for WCD 14.

On the other hand, if the IP PBX server 50 determines for some reason(such as based on the enterprise dialing plan or the WCD's configurationdata) that the call cannot be connected through to the called party, theIP PBX server 50 (or its associated media server) could play a speech ortone announcement to the caller, via the established bearer path.

b. Originating Outside Calls

In the next scenario, assume that WCD 14 places a call to a PSTN phonenumber, i.e., to a full PSTN number rather than an IP PBX extension,such as the phone number of telephone 30 for instance. (The PSTN numbercould be a DID number in the enterprise, but that does not matter.) Thisscenario is largely the same as the scenario described above, up untilthe point where a call path (or associated signaling) is established tothe IP PBX system, e.g., to the IP PBX server 50, except that the dialeddigits represent a full directory number rather than an abbreviated PBXextension.

In the preferred embodiment, once the IP PBX server 50 receives the callsetup request, the IP PBX server 50 may analyze the request and therebydetermine that it is a call to a PSTN number. (For instance, the factthat the dialed digits are the length or other form of a full directorynumber rather than the length or form of a simple extension number mayindicate that the call is a call to a PSTN number rather than to an IPPBX extension.) In response, the IP PBX server 50 may then set up thecall via a PSTN gateway. For instance, the IP PBX server 50 may engagein SIP signaling with MGC 80 to set up an RTP call leg between the IPPBX server 50 and another MGW 110 tied to the PSTN 24, and MGC 80 maycorrespondingly engage in SS7 ISUP signaling (e.g., via STP 26, with SP28) to set up the call from that MGW 110 via the PSTN 24 to the dialednumber (telephone 30). (Alternatively, IP PBX sever 50 could set up thecall to the outside number via a local telephone company switch.)

Advantageously, the call could thus proceed between WCD 14 and thecalled PSTN number, similarly leaving both signaling and bearer pathsthrough the IP PBX server 50. The IP PBX server 50 could thus manage theoutside call, to similarly provide IP PBX services, such as calltransfer, conference calling, and the like.

c. Terminating Outside Calls

In this next scenario, assume that MSC 22 receives a request to connectan outside call (i.e., a call from a PSTN directory number) to WCD 14.For instance, MSC 22 may receive an ISUP IAM request from anotherswitching point (e.g., SP 28) in the PSTN 24, seeking to set up a callto the directory number of WCD 14. (The call could come as a PSTN callfrom an outside line on the enterprise IP PBX system, but that does notmatter.)

Upon receipt of the call setup message, the MSC may then encounter a WINtrigger that points to SCP 32. Thus, MSC 22 may send an IS-41“AnalyzedInfo” message via the signaling network to the SCP, providingthe SCP with the calling and called numbers. SCP 32 may then refer to asubscriber profile store to determine that the WCD being calledsubscribes to IP PBX service. Thus, SCP 32 may send an AnalyzedInforeturn result to MSC 22, providing the MSC with the routing number ofMGC 80, to cause MSC 22 to set up the call to the media gateway system.

MSC 22 may then send an ISUP IAM call setup message via STP 26 to MGC80, providing MGC 80 with the calling and called numbers, and indicatingthat the call is a WCD-terminated call. MGC 80 may then generate andsend to CSCF 76 a corresponding SIP INVITE message that specifies thecalled number (namely, the WCD's number) as a telephone number URI inthe “To” field, and includes a header parameter indicating that this isa WCD-terminated call.

In this instance, given that the call is WCD-terminated, the CSCF 76 maythen dip into the correlation data 112 of HSS 82 to determine which hostIP PBX server serves the terminating cellular WCD (e.g., based on itsMDN) and may obtain from correlation data 112 a domain name of servingIP PBX server, such as IP PBX server 50. CSCF 76 may then responsivelyquery DNS server 92 to resolve the domain name into an IP address of IPPBX server 40, and CSCF 74 may route the INVITE to that IP address.

SIP signaling may then proceed between the MGC 80 and IP PBX server 50,via the CSCF 76, to set up a voice/RTP call leg between MGW 78 and IPPBX server 50. At the same time, ISUP signaling would pass between MGC80 and MSC 22 to set up a circuit-switched (e.g., PCM) call leg betweenMSC 22 and the MGW 78.

At this point, the IP PBX server 50 has thus received a signalingmessage seeking to set up a call to WCD 14. Further, the IP PBX server50 has a communication bearer path with WCD 14, via the RTP leg, MGW 78,the circuit leg, MSC 22, and cellular air interface 18. Thus, the IP PBXserver 50 can apply the enterprise dial plan to determine how to handlethe call.

Possible options for handling the call might include (i) ringing the WCD14, (ii) simultaneously or sequentially ringing the WCD 14 and acorresponding desk phone extension at the enterprise, or (iii) sendingthe call to the WCD's voice mail box at the enterprise IP PBX (or on theenterprise network). General logic, or configuration data for WCD 14,for instance, may indicate which of these or other options the IP PBXserver 50 should take. In an exemplary embodiment, for instance, IP PBXserver 50 might first ring WCD 14 and then, if no one answers, send thecall to voice mail or ring another enterprise extension. These variousoptions are discussed in the following subsections.

i. Ringing the Cellular WCD

When the IP PBX server 50 decides to connect a call to the WCD 14, theIP PBX server 50 may effectively initiate an outbound call (call leg) tothe WCD 14, via the media gateway system 74 and the RAN 12. To do so,the IP PBX server 50 could engage in SIP signaling with MGC 80, via theCSCF 76. For instance, the IP PBX server 50 could send a SIP INVITE thatseeks to set up a call to the directory number of WCD 14 (which wasindicated in the call setup message that the IP PBX server 50 hadreceived from the MGC 80. At that point, one of two processes (amongvarious others) could be applied.

In one process, MGC 80 could send an ISUP IAM to the WCD's home MSC.(Routing logic maintained or accessible by the MGC can correlate thedirectory number of WCD 14 with the home MSC.) In the exemplaryembodiment, the MGC would include in the IAM an indication that this isthe second leg of the call, or some other indication that the call hasalready been routed to the IP PBX system for handling, so as to avoidendless looping. The indication could be a user definable parameter inthe IAM message, provided that the home MSC (or SCP, if queried by thehome MSC) is programmed to interpret the parameter value as theindication. Upon receipt of the IAM, the home MSC would then encounter aWIN trigger that would cause the home MSC to send an IS-41“LocationRequest” (LOCREQ) message to the WCD's HLR 34. And the HLR 34then would return to the home MSC a LocationRequest return result(locreq_rr) that provides Advanced Termination Trigger directing thehome MSC to send an AnalyzedInfo message to the SCP 32.

The home MSC would then send an AnalyzedInfo message to the SCP 32, withan indication that this is a second leg of a call (based on theindication it received from MGC 80). Due to that indication, the SCP 32would send a “Continue” return result to the home MSC. And the home MSCwould then send another LOCREQ to the HLR to find out where the calledcellular WCD is currently located. Preferably, this second LOCREQ wouldinclude a trigger value that indicates this is a second LOCREQ and thatthe WCD location is to be determined, to preclude the HLR 34 from againproviding an Advanced Termination Trigger.

If WCD 14 is in the home MSC's serving system (i.e., if MSC 22 is thehome MSC), then the HLR would return a locreq_rr providing a “LocalDelivery” result, and so the MSC 22 would page/ring the cellular WCDand, if someone answers, connect the call through to the cellular WCD.Alternatively, if the WCD is in another MSC's serving system (i.e., ifMSC 22 is not the home MSC), then the HLR would send a RouteRequest(ROUTEREQ) to the serving MSC 22 and the MSC 22 would return aRouteRequest return result (routereq_a) providing a temporary localdirectory number (TLDN) to use for setting up the call to the cellularWCD. The HLR would then send a locreq_rr to the home MSC, providing theTLDN, and the home MSC would set up the call to the cellular WCD at thatTLDN, i.e., via MSC 22.

In another process, instead of MGC 80 signaling to the WCD's home MSCand the home MSC 22 signaling to the HLR 34 to find out where WCD 14 islocated, the MGC 80 could itself send a LOCREQ to the HLR 34 in aneffort to get a TLDN to which the MGC 80 can route the outbound call toWCD 14.

A problem with doing this normally would be that, like the home MSC asdescribed above, the MGC 80 would receive a locreq_rr that provides theMGC 80 with an Advanced Termination Trigger pointing to the SCP 32. Toavoid this, MGC 80 could include in its LOCREQ to HLR 34 a parameter (orlack thereof) indicating that the MGC 80 is not WIN-trigger capable. Asa result, HLR 34 would not return an Advanced Termination Trigger butwould instead proceed to send a ROUTEREQ to the WCD's serving MSC 22 soas to obtain a TLDN for the WCD. And HLR 34 would then send the TLDN toMGC 80 in a locreq_rr. Given the TLDN, MGC 80 could then engage in ISUPsignaling with the WCD's serving MSC 22, to set up the call to WCD 14 atthat TLDN, i.e., via MSC 22.

(Another way for MGC 80 to avoid receiving an Advanced TerminationTrigger from HLR 34 in response to a LOCREQ is for MGC 80 to indicate inthe LOCREQ that it is WIN-trigger capable, but to provide a trigger-typeof “location” rather than a trigger-type of “mobile termination.” Giventhat the trigger-type is “location,” HLR 34 would respond by providing aTLDN rather than providing an Advanced Termination Trigger.)

Once the call is connected to WCD 14, bearer and signaling paths wouldagain remain through the IP PBX server 40. Thus, once again, the IP PBXserver 40 could manage the call, providing IP PBX services, such as calltransfer, conference calling, and the like.

ii. Ringing Another IP PBX Extension

When the IP PBX server 50 decides to ring another IP PBX extension, theIP PBX server can simply engage in SIP signaling to set up the call tothe desired extension, in the manner described above for inside calloriginations. The IP PBX server 50 might do this after failing toconnect the call to WCD 14. Alternatively, the IP PBX server 50 might dothis at the same time as it seeks to connect the call to WCD 14, perhapsto simultaneously ring WCD 14 and the desk telephone of the WCD's user.In that case, the IP PBX server could connect the call through towhichever one answers the call first.

ii. Sending the Call to Voice Mail

If desired, the IP PBX server 50 could send the call to the WCD's voicemail box at the enterprise IP PBX system. To do so, the IP PBX server 50could engage in SIP signaling with the enterprise voice mail server 60or with another entity to connect the call to the enterprise voice mailserver 60.

d. Terminating Inside Calls

Assume next that another extension of the enterprise IP PBX system dialsthe extension that the IP PBX system has assigned to WCD 14. When thathappens, the IP PBX server 50 can determine how to handle the call.Possible handling options include, for instance, (i) ringing thecellular WCD, (ii) simultaneously or sequentially ringing the cellularWCD and a corresponding desk phone extension at the enterprise, or (iii)sending the call to the WCD's voice mail box at enterprise voice mailserver 60. These options are discussed in the following subsections.

i. Ringing the Cellular WCD

To ring WCD 14, the IP PBX server 50 can engage in SIP signaling withMGC 80 (via the CSCF 76), and MGC 80 can engage in ISUP signaling withMSC 22, as described above. With additional response signaling, a callpath could thus be set up from the IP PBX server 50 to the cellular WCD,via the media gateway system 74 and the RAN 12 serving the cellular WCD.

ii. Ringing Another IP PBX Extension

To ring another IP PBX extension, the IP PBX server 50 can apply itsnormal processes. The enterprise IP PBX server might do this afterfailing to connect the call to WCD 14. Alternatively, the enterprise IPPBX server might do this at the same time as it seeks to connect thecall to WCD 14, perhaps to simultaneously ring the cellular WCD and thedesk telephone of the cellular WCD's user. In that case, the enterpriseIP PBX server could connect the call through to whichever one answersthe call first.

iii. Sending the Call to Voice Mail

Similarly, if the IP PBX server decides to connect the call through tovoice mail, the enterprise IP PBX can do so through its normalprocesses, such as engaging in SIP signaling to connect the call to theenterprise voice mail server.

4. Centralized Master IP PBX Server

With the widespread popularity of VoIP communication, many enterprisesalready have IP PBX servers in place to serve their users on theirnetwork. Advantageously, the present system can be applied to extendthose existing IP PBX servers (or later acquired enterprise IP PBXservers) to serve users of cellular wireless devices as well.

One way to do so, as described above, is to provide a signaling andbearer path infrastructure between the enterprise IP PBX server and thecellular carrier's RAN, so the signaling and bearer path infrastructurecan connect calls between the RAN and the IP PBX server, and the IP PBXserver can thereby manage the calls in much the same way that the IP PBXserver manages calls for the telephone stations on the enterprise LAN.

As presently contemplated, another way to do so is to provide acentralized host IP PBX server in the carrier's network and to operatethe host IP PBX server as a “master” IP PBX server to handle calls forWCD extensions on the enterprise IP PBX system.

By way of example, the master IP PBX server could be the same make andmodel as the enterprise IP PBX server and could be configured largely(or fully) the same as the enterprise IP PBX server, so that the masterIP PBX server can offer the same services as the enterprise IP PBXserver. (A given master IP PBX server could be provisioned to servemultiple different enterprises, such as with partitioned logic andconfigurations for each enterprise for instance.)

More particularly, the master IP PBX server can be provisioned withconfiguration data for each WCD that is set as an extension on theenterprise IP PBX server (the slave IP PBX server), and theconfiguration data that the enterprise IP PBX server maintains for theWCD can direct the enterprise IP PBX server to turn to the master IP PBXserver for call handling when faced with a request to handle a call toor from a WCD. Yet the enterprise IP PBX server itself can be set tofully manage calls involving non-WCD extensions, without the need tointeract with the master IP PBX server.

In operation, the master IP PBX server can then engage in IP-based callsetup signaling with the MGC 80, via the CSCF 76, to establish RTPcommunication between MGW 78 and the master IP PBX server. Further, themaster IP PBX server can engage in both IP-based call setup signalingand RTP bearer communication with the enterprise IP PBX server, and theenterprise IP PBX server can in turn pass signaling and bearer databetween the master IP PBX server and the enterprise telephone stations.(In an alternative embodiment, the enterprise IP PBX server can functionas more than a mere conduit. For instance, it can apply some of its ownlogic to manage WCD calls as well.) Thus, the master IP PBX server wouldfunction as IP PBX server 50 in the description above, though itscommunications with enterprise telephone stations may pass through theapplicable enterprise IP PBX server.

An advantage of this arrangement is that it allows the wireless carrierto better manage operation of the IP PBX system, such as to ensure thatthe IP PBX system and other entities (e.g., HLR, SCP, and media gatewaysystem) are appropriately configured to facilitate serving WCDextensions on enterprise IP PBX system. Further, it can provide acentralized point (the master IP PBX server) with which variousenterprise IP PBX servers can be set to communicate, rather than havingIP PBX server be set to communicate with more likely many MGCs(distributed in various locations throughout a cellular carrier'snetwork).

FIG. 6 depicts an example of this master IP PBX server arrangement. Asshown in FIG. 6, MGC 80 and CSCF 76 are communicatively linked with acarrier's core packet data network 300. Further sitting as other nodeson network 300 are two representative master IP PBX servers 302, 304.Master IP PBX server 302 is an IP PBX server of “Type A,” and master IPPBX server 304 is an IP PBX server of “Type B.” Types A and B could beparticular makes and models or particular configurations, for instance.By way of example, Type A could be an Avaya S8700 IP PBX server forinstance, whereas Type B could be some other make and model IP PBXserver.

Network 300 is then coupled with a plurality of enterprise networks 306,308, 310. Further, sitting as a node on each enterprise network is arespective enterprise IP PBX server as well as a number ofrepresentative enterprise IP PBX telephone stations. In particular,sitting as nodes on enterprise network 306 are an enterprise IP PBXserver 312 and representative enterprise telephone stations 314, 316;sitting as nodes on enterprise network 308 are an enterprise IP PBXserver 318 and representative enterprise telephone stations 320, 322;and sitting as nodes on enterprise network 310 are an enterprise IP PBXserver 324 and representative enterprise telephone stations 326, 328. Asfurther shown by way of example, IP PBX servers 312 and 324 (onenterprise networks 306, 310) are of Type A, and IP PBX server 318 (onenterprise network 308) is of Type B.

FIG. 6 also depicts three representative WCDs 330, 332, 334, each ofwhich may be set as extensions on one of the various enterprise IP PBXsystems illustrated. For each WCD, the corresponding master IP PBXserver (of the same type as the enterprise IP PBX server that serves theWCD) may thus have configuration data for the WCD, largely the same asthe enterprise IP PBX server would be configured for the WCD if themaster IP PBX server did not exist. For instance, WCD 330 may be set asan extension on enterprise IP PBX server 312, and master IP PBX server302 (of the same type as enterprise IP PBX server 312) may includeconfiguration data for WCD 330; WCD 332 may be set as an extension onenterprise IP PBX server 318, and master IP PBX server 304 (of the sametype as enterprise IP PBX server 318) may include configuration data forWCD 332; and WCD 334 may be set as an extension on enterprise IP PBXserver 324, and master IP PBX server 302 (of the same type as enterpriseIP PBX server 324) may include configuration data for WCD 334.

With this arrangement, for example, when MGC 80 receives a request fromMSC 22 to set up a call to or from WCD 330, MGC 80 may signal to CSCF76, and CSCF 76 may dip into HSS 82 and reference correlation data 112to thereby determine that master IP PBX server 302 serves the WCD. (Inone embodiment, for instance, the correlation data may associate WCD 330with enterprise IP PBX server 312 and may then associate IP PBX server312 with master IP PBX server 302.) CSCF 76 may thus pass the callssetup signaling message to master IP PBX server 302. Master IP PBXserver 302 may then apply the enterprise PBX dialing plan (correspondingto enterprise IP PBX server 312) and the configuration data of WCD 330to determine how to handle the call. In the event master IP PBX server302 determines that the call should be connected in turn to an extensionon the enterprise network 306, master IP PBX server 302 may then set upthe call through enterprise IP PBX server 312 to that extension.

As another example, when MGC 80 receives a request from MSC 22 to set upa call to or from WCD 332, MGC 80 may signal to CSCF 76, and CSCF 76 maydip into HSS 82 and reference correlation data 112 to thereby determinethat master IP PBX server 304 serves the WCD. MGC 74 may thus engage incall setup signaling to set up the call with master IP PBX server 304.Master IP PBX server 304 may then apply the enterprise PBX dialing plan(corresponding to enterprise IP PBX server 318) and the configurationdata of WCD 332 to determine how to handle the call. In the event masterIP PBX server 304 determines that the call should be connected in turnto an extension on the enterprise network 308, master IP PBX server 304may then set up the call through enterprise IP PBX server 318 to thatextension.

5. IP Centrex as Hosted IP PBX

In yet another embodiment, the functionality of an enterprise IP PBXserver can be provided entirely by a telecommunications carrier or otherentity, such as a wireless carrier for instance, with or without an IPPBX server being situated at the enterprise as well. More particularly,the IP PBX server can take the form of an IP Centrex server that sits ona carrier's packet network and that is connected through one or morerouters or gateways with the enterprise network.

With this arrangement, packet-based call setup signaling can flowbetween the enterprise network and the IP Centrex server, to allow theIP Centrex server to set up inside calls within the enterprise as wellas outside calls to or from the enterprise, just as another sort of IPPBX server would do. Further advantageously, like the hosted IP PBXserver described above, an IP Centrex server can be arranged to servemultiple different enterprises, with partitioned logic for instance.

6. Selective Check-In/Check-Out Logic

As noted above, the integration of cellular telephone service with IPPBX service can provide a significant benefit, in that it allows a userto enjoy IP PBX service features when the user is out of the office andoperating a cellular telephone, theoretically anywhere within thecoverage provided by the user's wireless carrier. By the same token,however, there may be times when a user who subscribes to such servicedoes not want the service to apply. For instance, during evenings andweekends, the user may want his or her cell phone to function as apersonal cell phone, not tied to the user's work IP PBX system, butduring weekdays when the user is out of the office, the user may wanthis cell phone to function as an IP PBX extension.

To account for this desire, logic can be added to enable a WCD user to“check in” and “check out” of the cellular-PBX integration service, suchas by allowing the user to activate and deactivate the service or tohave a defined schedule that indicates when the service should apply andwhen it should not apply. Such logic can be implemented in various wayswithin the example system described above. Two example implementationsare described in the following subsections.

a. Personal-Enterprise Policy Server

According to a first embodiment, HSS 82 will maintain in the WCD'sprofile an indication of whether the WCD is currently checked-into orchecked-out of the system. The indication may be a Boolean flag that auser can set or clear to indicate whether the cellular-PBX integrationfunction should apply or not. When the flag is set, the WCD would betreated as an extension of the IP PBX system, such as in the mannerdescribed above. And when the flag is cleared, the WCD would be treatedas a conventional WCD, allowing personal cellular service withoutcellular-PBX integration. Alternatively, the indication in the WCD'sprofile may take the form of a schedule that indicates specific times(e.g., times of day, days of week, dates, etc.) when the cellular-PBXintegration function should apply and other times when it should notapply.

Preferably, the user will provision the settings in the profile byinteracting with a web based provisioning interface provided by a webserver tied to the HSS. For instance, the user may employ a generic webbrowser on the user's WCD or personal computer to browse to an addressof the web server and, after being authenticated, may receive a reportof the current profile settings and make changes to the profilesettings. As the user thereby checks-in or checks-out (e.g., by settingor clearing a Boolean flag) or changes a check-in/check-out schedule,the web server would then preferably populate or update the WCD'sprofile in HSS 82 accordingly (e.g., by writing directly to the profile,or by sending a signal to another entity to update the profile).

This check-in/check-out process can change the example operationdescribed above in various ways, a number of which are described in thefollowing subsections. These example variations can be extended byanalogy to other cellular-PBX integration functions as well. Further, itshould be understood that the specific variations described below areset forth by way of example only and that numerous alternatives arepossible.

i. Terminating Outside Calls

When a call is placed to the directory number of WCD 14, as describedabove, MSC 22 would receive a request to terminate the call and (asinstructed by SCP 32, for instance) would responsively set up the callto media gateway system 74. In particular, MSC 22 would engage in ISUPsignaling with MGC 80. In the process, MGC 80 would then send to CSCF 76a SIP INVITE message that specifies in the “To” field the calledtelephone number, which is the directory number of the WCD.

In accordance with the exemplary embodiment, the CSCF 76 will thenresponsively dip into HSS 82 and thereby determine that the callednumber is assigned to an account that subscribes to cellular-PBXintegration service. In response to the determination that the calledWCD subscribes to cellular-PBX integration service, the CSCF 76 willprogrammatically route the INVITE or a corresponding message to PEpolicy server 94 to enable a determination of whether the WCD iscurrently checked-into or checked-out of the service.

To make this happen, the HSS profile for the WCD may specify a domainname for the PE policy server 94, such as “pe-policy.com”, or CSCF 76may be programmed with an indication of that domain name. The CSCF 76may then append that domain name to the end of the telephone number URIin the “To” field of the SIP INVITE, so as to create a full SIP addressin the form “+9876543210@pe-policy.com” To route that SIP INVITE, theCSCF 76 may then dip into the DNS server 92 to determine an IP addresscorresponding to that domain name and may then transmit the INVITE tothat IP address, i.e., to the PE policy server 94.

Upon receipt, the PE policy server 94 will then programmatically analyzethe called number and will itself dip into HSS 82 to determine whetherthe called WCD is currently checked-into or checked-out of thecellular-PBX integration function.

If the PE policy server 94 thereby determines that the called WCD is notchecked into the system (i.e., is currently checked out of the system),the PE policy server 94 will then signal back to the CSCF 76 to causethe CSCF 76 to set up the call back to the media gateway system 74 forconnection back to MSC 22 and to the WCD 14.

To do this in practice, the PE policy server 94 can insert in the SIPINVITE a predetermined code that will direct the CSCF 76 to set up thecall back to the media gateway system 74, and may then send the INVITEback to the CSCF 76. In one embodiment, for instance, the predeterminedcode could be a sequence of five “9”s prepended to the called number inthe “To” field, but it could take other forms and be set forth in someother manner in the INVITE, provided that the CSCF is programmed todetect the code and respond accordingly. Further, the PE policy serveror the CSCF can strip the PE policy server domain from the “To” field ofthe INVITE message to direct call setup to the directory number of theWCD. Alternatively, the PE policy server 94 can change the URI in the“To” field to include a domain name of the MGC 80.

When CSCF 76 receives the INVITE and detects the predetermined code ordomain, the CSCF will responsively send the INVITE or a correspondingmessage to MGC 80, seeking to set up the call to the directory number ofWCD 14. The MGC 80 will then responsively engage in ISUP signaling withMSC 22 to set up the call to the WCD.

On the other hand, if the PE policy server 94 determines that the calledWCD is currently checked into the cellular-PBX integration service, thePE policy server 94 will then signal back to the CSCF 76 to cause theCSCF 76 to set up the call to IP PBX server 50. To do this in practice,the PE policy server 94 may determine from the WCD's HSS profile adomain name of the IP PBX server that serves the WCD, such as“ippbx50.com”, and the PE policy server 94 may substitute that domainname in the “To” field of the SIP INVITE. The PE policy server 94 maythen send that INVITE to the CSCF 76. To route the INVITE, the CSCF 76may then dip into DNS server 92 to determine an IP address correspondingto that domain name and may then transmit the INVITE to that IP address,i.e., to IP PBX server 50. Processing can then continue as describedabove.

ii. Terminating Inside Calls

In accordance with the exemplary embodiment, when a call is placed tothe WCD's assigned PBX extension, the IP PBX server 50 willprogrammatically send a SIP INVITE to the CSCF 76, to facilitate adetermination of whether the WCD is currently checked-in or checked-outand to facilitate appropriate handling of the call. Preferably, the IPPBX server 50 will include as the called number in the “To” field of theSIP INVITE the 10-digit directory number of the WCD. Further, the IP PBXserver 50 may include in the INVITE a predetermined code that willfunction as a programmatic directive to cause the CSCF to signal to PEpolicy server 94. For instance, the IP PBX server 50 can prepend five“8”s to the directory number, and the CSCF can be programmed tointerpret the five “8”s as an indication that the CSCF shouldresponsively signal to the PE policy server 94.

Upon receipt of the INVITE from the IP PBX server 50, the CSCF 76 willthus send the INVITE or a corresponding message to the PE policy server94, preferably first stripping the prepended digits from the directorynumber. The PE policy server 94 will then analyze the called number andwill dip into HSS 82 to determine if the called WCD is currentlychecked-into or checked-out of the cellular-PBX integration function.

If the PE policy server 94 thereby determines that the called WCD is notchecked into the system, the PE policy server 94 will then signal backto the CSCF 76 to cause the CSCF 76 to set up the call back to the IPPBX server 50. For instance, the PE policy server 94 can include in themessage a predefined code that the CSCF 76 would interpret as aninstruction to not pass the call to the WCD. In this instance, the CSCF76, which has a pending SIP INVITE from the IP PBX server 50, willpreferably send a SIP response message to the IP PBX server 50,indicating that the call cannot be completed to the WCD. For example,the CSCF can send a SIP REDIRECT message, redirecting the call to theWCD's voice mail box, or the CSCF can send some other SIP “unavailable”message. The IP PBX server 50 can then operate as it normally does whena call cannot be completed.

On the other hand, if the PE policy server 94 determines that the WCD iscurrently checked into the system, then the PE policy server 94 willsend a signal to the CSCF 76 that will cause the CSCF 76 to route thecall to the media gateway system for connection in turn to MSC 22 and tothe WCD 14.

One way to do this in practice is for the PE policy server 94 to removethe prepended “8”s from the called number and replace them with asequence of five “9”s prepended to the called number, and then send theSIP INVITE to the CSCF 76. As above, when the CSCF 76 receives an INVITEthat has the five “9”s prepended to the called number (or contains someother predetermined code), the CSCF 76 will responsively send the INVITEto MGC 80 (preferably after first stripping the prepended “9”s), to setup the call to the called number. Upon receipt of the INVITE, MGC 80would then engage in ISUP signaling with MSC 22 to set up the call tothe WCD.

iii. Originating Calls from the WCD

When WCD 14 initiates a call to a set of dialed digits, the processdescribed above would apply to set up the call to media gateway system74 and provide a SIP INVITE to CSCF 76. In particular, at theinstruction of SCP 32, MSC 22 may set up the call to media gatewaysystem 74, and MGC 80 may then send a SIP INVITE to CSCF 76. The INVITEwould preferably include a predetermined code or other indication thatthe calling number, in the “From” field, is a WCD.

In response to the INVITE, the CSCF 76 will then responsively dip intoHSS 82 and thereby determine that the calling number is assigned to anaccount that subscribes to cellular-PBX integration service. In responseto the determination that the calling WCD subscribes to cellular-PBXintegration service, the CSCF 76 will programmatically route the INVITEor a corresponding message to PE policy server 94 to enable adetermination of whether the WCD is currently checked-into orchecked-out of the service.

If the PE policy server 94 determines that the calling WCD is notchecked into the system, the PE policy server 94 will responsively senda signal to the CSCF 76 to cause the CSCF 76 to set up the call back tothe media gateway system 74. The PE policy server 94 can do this in theways described above for instance, such as by changing the URI of thecalled party to include an MGC domain name, or by including in theINVITE a predetermined code that will direct the CSCF 76 to route theINVITE to the MGC 80. In either case, the MGC 80 will then set up thecall back through MSC 22, to allow MSC 22 to handle the callconventionally, such as by attempting to connect the call through thePSTN to the called party.

On the other hand, if the PE policy server 94 determines that thecalling WCD is checked into the system, then the PE policy server 94will send a signal to the CSCF 76 to cause the CSCF 76 to route the callto the IP PBX server 50 for handling. In the manner described above, forinstance, the PE policy server 94 can apply an IP PBX server domain nameto the called URI in the “To” field, and the CSCF 76 can then dip intothe DNS server 92 and route the INVITE to the corresponding IP addressof IP PBX server 50. Processing can then continue as described above.

b. SCP as Policy Server

According to an alternative embodiment, SCP 32 (rather than, or inaddition to, HSS) will maintain in the WCD's profile an indication ofwhether WCD is currently checked-into or checked-out of the system,and/or a schedule that indicates times when the WCD is checked-in andtimes when the WCD is checked-out. As with the HSS profile discussedabove, a user will preferably provision this profile through a web-basedinterface. Alternatively, feature-codes (e.g., # or * codes) could bedefined to allow the user to check-in and check-out of the service asrecorded in the WCD's SCP-based profile record.

As an alternative, HSS 82 could maintain the profile record for the WCDas in the above embodiment, and SCP 32 could be programmed (or directedby WCD profile parameters) to dip into HSS 82 to determine whether theWCD is currently checked-in or checked-out. For this purpose, the SCP 32could be provided with a packet-network connection, through which it cancommunicate with the HSS, such as by sending a remote procedure call orthe like. Still alternatively, the SCP 32 and HSS 82 could be integratedtogether as a common network entity.

The following subsections discuss how this embodiment may operate tohandle call origination from the WCD and call termination to the WCD.

i. Terminating Calls to the WCD

When MSC 22 receives a request to terminate a call to the WCD'sdirectory number, the MSC will encounter an intelligent network triggerand will responsively signal to the SCP 32, sending an AnalyzedInfomessage indicative of a call termination attempt. By reference to theWCD's profile record, the SCP will then determine whether the called WCDis currently checked-into or checked-out of the cellular-PBX integrationservice.

If the SCP determines that the WCD is not checked into the system, theSCP will signal back to the MSC, directing the MSC to conventionallyhandle the call termination, and the MSC will then do so. On the otherhand, if the SCP determines that the WCD is checked into the system,then the SCP will signal back to the MSC, directing the MSC to set upthe call to the media gateway system. The MSC will then do so, andprocessing will continue as described above for instance.

ii. Originating Calls from the WCD

When the MSC receives a request from the WCD to originate a call, theMSC will similarly encounter a trigger and responsively signal to theSCP, sending an Origination Request indicative of a call originationattempt. The SCP will then determine whether the calling WCD iscurrently checked-into or checked-out of the system.

If the SCP determines that the WCD is not checked into the system, theSCP will signal back to the MSC, directing the MSC to conventionallyhandle the call origination, and the MSC will then do so. On the otherhand, if the SCP determines that the WCD is checked into the system, theSCP will signal back to the MSC, directing the MSC to set up the call tothe media gateway system. The MSC will then do so, and processing willcontinue as described above for instance.

c. Using Other Party as Basis for Deciding Whether to Apply Cellular-PBXIntegration

As an alternative or additional embodiment, the identity of the partywith whom the WCD is engaging in a call can be used as a basis todetermine whether to apply cellular-PBX integration or not. In thisregard, the WCD's profile (e.g., at HSS 82 and/or SCP 32) could includea listing of directory numbers and/or PBX extensions with respect towhich cellular-PBX integration should be applied and/or a listing ofdirectory numbers and/or PBX extensions with respect to whichcellular-PBX integration should not apply.

When an entity such as PE policy server 94 or SCP 32 seeks to determinewhether to apply cellular-PBX integration, the entity may then refer tothe WCD's profile to determine whether the party with whom the callwould be connected is one for which cellular-PBX integration should beapplied. For instance, for an outgoing call from WCD 14, the decisioncould be based on the dialed digits, while, for an incoming call to WCD14, the decision could be based on the telephone number or extension ofthe calling party.

By way of example, a WCD user may specify in his or her profile thatcalls to or from the user's spouse should be not be treated ascellular-PBX integration calls, so that the a call between the WCD'sdirectory number and the spouses telephone number would not be routedthrough the IP PPX server 50. On the other hand, a WCD user may specifyin his or her profile that calls to or from the user's work colleaguesor boss should be treated as cellular-PBX integration calls, so that acall between the WCD and the boss's telephone number would be routedthrough the IP PBX server 50. Other examples are possible as well.

In this regard, the act of determining, based at least in part on theother party's identity, whether or not to apply cellular-PBX integrationcan be considered another manner of determining whether or not the WCDis “checked-in” or “checked-out” on a per-call basis. If thedetermination is to not apply cellular-PBX integration due in part tothe identity of the other party, then the WCD can be considered“checked-out.” Whereas, if the determination is to apply cellular-PBXintegration due in part to the identity of the other party, then the WCDcan be considered “checked-in.”

c. Example Process Flow

FIGS. 7 and 8 are flow charts depicting example sets of functions thatcan be carried out to provide selective check-in/check-outfunctionality.

As shown in FIG. 7, at step 300, a WCD's profile record is provisionedto indicate whether the WCD is checked-into or checked-out of acellular-PBX integration service. At step 302, a RAN serving the WCDreceives a call request for the WCD. At step 304, a first leg of thecall is requested to be set up between the RAN and a media gatewaysystem, and call setup signaling is sent from the media gateway systemto a CSCF.

At step 306, a determination is made as to whether the WCD is currentlychecked-into or checked-out of the cellular-PBX integration service,such as by reference to the profile record. If the determination is thatthe WCD is checked-in, then, at step 308, the call setup signaling ispassed from the CSCF to an IP PBX server that serves the WCD, to requestset up of a second leg of the call from the media gateway system to theIP PBX server. On the other hand, if the determination is that the WCDis currently checked-out, then, at step 310, then signaling is passedback from the CSCF to the media gateway system to request setup of thecall back from the media gateway system to the RAN.

As shown in FIG. 8, at step 312, a WCD's profile record is provisionedto indicate whether the WCD is checked-into or checked-out of acellular-PBX integration service. At step 314, a RAN serving the WCDreceives a call request for the WCD. At step 316, the RAN signals to anSCP for call processing guidance. At step 318, the SCP determineswhether the WCD is currently checked-into or checked-out of thecellular-PBX integration service, such as by reference to the profilerecord. If the determination is that the WCD is checked-in, then, atstep 320, the SCP directs the RAN to set up the call to a media gatewaysystem for connection in turn to an IP PBX server that serves the WCD.On the other hand, if the determination is that the WCD is checked-out,then, at step 322, the SCP directs the RAN to handle the call as normal.

7. Selective Voice-Mail Routing

As illustrated in the figures and described above, voice mail servicemay be provided by both a cellular wireless carrier and an enterprise IPPBX system. For instance, as shown in FIG. 4, a voice mail server 86provided by a cellular carrier may reside on packet-switched network 90,and the carrier's media gateway system 74 may be arranged to connectunanswered, blocked or busy calls to that voice mail server 86. Further,another voice mail server 60 may be provided on an enterprise network,and IP PBX server 50 may be arranged to connect unanswered, blocked orbusy calls to that voice mail sever 60.

With cellular-PBX integration, the existence of separate cellular andenterprise voice mail systems raises an issue of which voice mail systemto apply in a given instance. For instance, when the WCD user seeks tocheck the WCD's voice mail (such as by dialing the directory number ofthe WCD), at issue is whether the WCD should be connected to the WCD'svoice mail box on the cellular voice mail system or rather to the WCD'svoice mail box on the enterprise voice mail system. Similarly, whenanother party calls the WCD's directory number or the WCD's IP PBXextension and the call is unanswered, blocked, or busy, at issue iswhether the caller should be connected to the WCD's cellular voice mailbox or rather to the WCD's enterprise voice mail box.

One way to handle this issue, in accordance with the exemplaryembodiment, is to introduce voice mail (VM) policy server 98 into thecellular-PBX integration system, as shown in FIG. 4, and to configurethe system to invoke the VM policy server 98 when a need arises toselect a destination voice mail box. For instance, when CSCF 76 is toroute a call to the voice mail box of WCD 14, CSCF 76 may send a SIPsignal to the VM policy server 98, and the VM policy server 98 maydetermine whether to connect the call to the WCD's cellular voice mailbox or to the WCD's enterprise voice mail box. The VM policy server 98may then signal back to the CSCF 76 in a manner that directs CSCF 76 toroute the call to the selected voice mail box.

VM policy server 98 can decide in various ways which voice mail servershould handle a given call. In one embodiment, for instance, VM policyserver 98 can dip into HSS 82 and determine based on the WCD's profilewhich voice mail server to use. In this regard, the WCD's profile couldspecify voice mail systems to use depending on the calling party, thetime of day, or other factors. Alternatively, the decision of whichvoice mail system to use can be keyed to whether the WCD is currentlychecked-into or checked-out of the system, such as by selecting theenterprise voice mail system if the WCD is checked-in and selecting thecellular voice mail system if the WCD is checked-out.

In an alternative embodiment, however, the VM policy server 98 willpreferably include, embody, or be interconnected with an integratedvoice response unit (IVRU), such as a voice-XML (VXML) based platform,as depicted in FIG. 4 for instance. The process of invoking the VMpolicy server 98 can then involve connecting the calling party to theIVRU. Once connected, the IVRU may then prompt the calling party toselect a voice mail system for handling the call. In response to thecaller's selection, the IVRU may then direct the CSCF 76 to redirect thecall to the selected voice mail server.

Advantageously, this arrangement gives the caller more direct controlover the voice mail routing decision for a given called WCD. In someinstances, a caller may opt to have a call connected to the WCD'scellular voice mail box, and in other instances, a caller may opt tohave a call to the same number connected instead to the WCD's enterprisevoice mail box.

The following subsections discuss example functions that can be carriedout in this manner, (a) when the WCD is to be connected to its own voicemail box and (b) when another party is to be connected to the WCD'svoice mail box. As with the other embodiments described herein, manyvariations from the functions described are possible.

a. WCD Call to Voice Mail

In order for the WCD to connect with its own voice mail box, the WCD maydial its own directory number, so as to force a connection with voicemail. (Alternatively, a feature code or other mechanism could be definedto trigger a connection with voice mail. Generally, any call request toconnect with voice mail can be considered a “voice mail call request.”)When that happens, MSC 22 will engage in ISUP signaling with MGC 80 toset up the call to media gateway system 74 in the manner described abovefor instance. MGC 80 will then send a SIP INVITE for the call to CSCF76, with the INVITE specifying the same number in both the calling(“From”) and called (“To”) fields.

Upon receipt of the INVITE, the CSCF 76 will then detect that thecalling and called numbers are the same and will therefore conclude thatthe WCD is attempting to call itself. In response, the CSCF 76 will dipinto the WCD's profile in HSS 82 to ascertain (i) the domain or IPaddress of the IVRU (VM policy server) 98, and (ii) descriptors anddomain names or IP addresses of the voice mail servers that areavailable to handle the call, i.e., the voice mail servers that hostvoice mail boxes for the WCD.

The CSCF 76 will then forward the SIP INVITE or send a correspondingmessage to the IVRU (first dipping into DNS server 92 if necessary), andwould provide within the SIP INVITE a directive for the IVRU to promptthe caller to select a voice mail system. By way of example, the CSCF 76may include in one or more SIP header parameters in the INVITE a VXMLscript will cause the IVRU to play out a prompt such as “Press 1 forpersonal (cellular) voice mail, or press 2 for corporate (enterprise)voice mail,” and that links each choice to a respective URL tying theWCD's number with a given voice mail server. Assuming the WCD's callednumber is 9876543210, for instance, choice 1 could be linked to the URL“+9876543210@cellular-vms.com”(for voice mail server 86) and choice 2could be linked to the URL “+9876543210@enterprise-vms.com” (for voicemail server 60).

At that point, the IVRU may engage in continued SIP signaling (e.g., 200OK/ACK) with the MGC 80, via the CSCF 76, so that a bearer path can beset up between the MGW 78 and the IVRU and thus ultimately between thecalling WCD and the IVRU. Once connected, the IVRU will then play outthe specified prompt to the calling WCD, and the IVRU will receive fromthe WCD a spoken or DTMF selection of the desired voice mail server.

Provided with the a selection of a desired voice mail server, the IVRUwill then preferably send to the CSCF 76 a SIP REDIRECT message that maypass in turn to the MGC 80 (or stop wherever the SIP signalinginitiated). The SIP REDIRECT will include as a redirect-URL the URL thatwas associated with the selected voice mail server, such as“+9876543210@cellular-vms.com” or “+9876543210@enterprise-vms.com”. TheMGC 80 (or other initiating SIP endpoint) would then send a SIP INVITEto the newly designated URL and engage in further SIP signaling toestablish a bearer path between the caller and the selected voice mailserver. Further, the telephone number in the URL would indicate to thevoice mail server that the call is to be connected to the WCD's voicemail box.

If the selected voice mail server is the cellular voice mail server 86,then the SIP signaling would thus pass through network 90 between MGC 80and voice mail server 86. On the other hand, if the selected voice mailserver is the enterprise voice mail server 60, then the SIP signalingwould pass through network 90 between MGC 80 and voice mail server 60.In a preferred embodiment, as shown in FIG. 4, enterprise voice mailserver 60 will be tied directly to network 90 to facilitate thissignaling and to enable a resulting bearer path to extend from MGW 78 tothe enterprise voice mail server 60 without involving the IP PBX server50. Alternatively, however, the signaling and bearer path to connectwith enterprise voice mail server 60 could extend through IP PBX server50, but precautions would be put in place to avoid an endless loopcondition.

b. Third Party Call to WCD's Voice Mail

When a third party places a call to the WCD (either to the WCD'sdirectory number or its IP PBX extension) and the call is unanswered,blocked, or busy, CSCF 76 will preferably receive a SIP message, such asa SIP BUSY, that indicates the call cannot be connected to the WCD. Thesame process described above for a WCD initiated call to voice mail willthen apply, although the caller would be a third party rather than theWCD itself.

Thus, the CSCF 76 may dip into HSS 82, and send a signal to the IVRU ofVM policy server 98, the IVRU would prompt the caller to select a voicemail server to handle the call, and the IVRU would then send a SIPREDIRECT or otherwise direct the call to be connected to the WCD's voicemail box on the selected voice mail server.

c. Example Process Flow

FIG. 9 is a flow chart depicting an example set of functions that can becarried out to provide dynamic voice mail routing. As shown in FIG. 9,at step 324, a RAN receives a voice mail call request for a subscriber(such as a call from the subscriber to the subscriber's voice mail, or acall from a third party that is not connected to the subscriber). Atstep 326, a first leg of the call is set up from the RAN to a mediagateway system. At step 328, a second leg of the call is set up from themedia gateway system to an automated voice response system. At step 330,the automated voice response system prompts the caller to select a voicemail system from among a plurality of voice mail systems. At step 332,the automated voice response system receives a selection of a voice mailsystem from the caller. At step 334, the second leg is then connectedinstead from the media gateway system to the selected voice mail systemfor handling.

(In an alternative embodiment, the call can remain connected through theautomated voice response system, to the selected voice mail system. Andin another alternative embodiment, the automated voice response systemcan itself function as the selected voice mail system, in which case thesecond leg can remain connected to the automated voice response systembut can then be handled as a call to voice mail would be handled.)

d. SCP-based Selective Voice Mail Routing

In an alternative embodiment, SCP 32, alone or in combination with oneor more intelligent peripherals or other entities, can provide forselective voice mail routing. By way of example, if MSC 22 determinesthat a call cannot be connected to the called WCD, MSC 22 may encountera WIN trigger that causes MSC 22 to signal up to SCP 32. SCP 32 may thenresponsively consult the WCD's profile record and determine which ofmultiple voice mail systems should receive the call.

In the exemplary embodiment, the MSC 22 would have trunk connections(not shown) or other links with the various voice mail systems, such asservers 60 and 86, so MSC 22 can set up the call to a selected voicemail system via such a trunk. Alternatively, MSC 22 could set up thecall to a selected voice mail system via media gateway system 74.

As with the process described above, for instance, the SCP may directthe MSC to set up the call to a given voice mail system if the WCD iscurrently checked-into the cellular-PBX integration service, and the SCPmay direct the MSC to set up the call to a different voice mail sever ifthe WCD is currently checked-out of the cellular-PBX integrationservice. The SCP could apply still other logical conditions as a basisto select which voice mail system should receive the call.

Alternatively, the SCP could first direct the MSC 22 to set up the callto a voice response platform that can operate in the manner describedabove to allow the caller to select a voice mail system, and the voiceresponse platform may signal to the SCP to instruct the SCP which voicemail system should receive the call. The SCP may then direct the MSC 22to set up the call to the selected voice mail system. Other arrangementsare possible as well.

8. Temporary Bypass or Application of Cellular-PBX Integration

As presently contemplated, the selective check-in/check-out logicdescribed above will enable a user to effectively activate or deactivatethe cellular-PBX integration service. In some instances, however, a WCDuser may want to temporarily bypass or apply the cellular-PBXintegration feature, without turning on or off the service. Forinstance, when the WCD's profile indicates that the WCD is checked-in,the user of the WCD may want to place a personal call that does not getrouted through the IP PBX system. Similarly, when the WCD's profileindicates that the WCD is checked-out, the user may want to place a callthrough the IP PBX system.

To account for this desire, logic can be added to enable a WCD user tobypass or apply cellular-PBX integration on a per-call basis. That is,logic may be provided to allow a user to check-in or check-out a WCD ona per-call basis, possibly overriding the normal check-in/check-outstatus indicated by the WCD's profile. Two embodiments of this processare described in the following subsections, again with understandingthat numerous variations are possible.

a. Feature-Code Based Per-Call Bypass or Application

According to a first embodiment, when a user dials a call on WCD, theuser can include with the dialed digits a predefined feature code thatwill toggle the cellular-PBX integration function for that call only. Ifthe WCD is currently checked-in, the feature code will causecellular-PBX integration to not apply for the call, and if the WCD iscurrently checked-out, the feature code will cause the cellular-PBXintegration function to apply for the call. Alternatively, separate“bypass” and “apply” feature codes could be defined respectively for notapplying cellular-PBX integration and for applying cellular-PBXintegration.

When the WCD sends a call origination request with such a feature codeappended to the dialed digits, the MSC 22 can signal to SCP 32, and SCP32 can respond to the feature code by either directing the MSC 22 toconnect the call to media gateway system 74 or not. For instance, if thefeature code is a temporary bypass directive (or if SCP profile dataindicates that the WCD is currently checked-in and the feature code is atoggle code), then the SCP would preferably direct the MSC 22 to handlethe call as a normal cellular call, without causing the call to berouted to the media gateway system 74 and CSCF 76. On the other hand, ifthe feature code is a temporary apply directive (or if SCP profile dataindicates that the WCD is currently checked-out and the feature code isa toggle code), then the SCP would preferably direct the MSC 22 to setup the call to the media gateway system, and cellular-PBX processingwould occur as described above.

As an alternative, the dialed feature code can accompany the dialeddigits that are provided in a SIP signaling message to CSCF 76, and CSCF76 or an applicable policy server (such as TOD policy server 94 forinstance) can be invoked based on the feature code to determine whetherto apply cellular-PBX integration or not. The process described abovefor call handling in response to a “check-out” or “check-in”determination would then occur. Thus, CSCF 76 would either route thecall to IP PBX 50 (if cellular-PBX integration is to be applied for thecall) or back to the media gateway system 74 (if cellular-PBXintegration is not to be applied for the call).

b. IVR Prompted Selection to Bypass or Apply

In another embodiment, the IVRU function described above with respect tothe VM policy server 98 can be varied in a way that will let the WCDuser select whether to bypass or use the cellular-PBX integrationservice for the current call. Alternatively, a separate IVRU or otherautomated voice response system can be provided to carry out thefunction in a similar manner, with or without also relating to voicemail server selection.

In this embodiment, by way of example, the HSS profile for the WCD willspecify that when the WCD calls its own number, the WCD user may beprompted not only to select a voice mail server to receive the call, butalso with an option to dial digits that will be out-dialed withoutpassing through the IP PBX server 50, i.e., to bypass cellular-PBXintegration.

Based on such a profile, for instance, when CSCF 76 receives a SIPINVITE seeking to set up a call from WCD 14 to WCD 14, the CSCF woulddip into HSS 82 as described above and would receive information thatcauses the CSCF to set up the call to the IVRU and to direct the IVRU toprompt the caller for a selection. The prompt may, for instance, state“Press 1 for personal voice mail, press 2 for corporate voice mail, orpress 3 to dial digits and place a call without cellular-PBXintegration.”

Once the IVRU plays out such a prompt, if the user selects “3”, the IVRUmay then prompt the user to dial digits in order to place a phone call.Upon receipt of the dialed digits, the IVRU may then set up and bridge acall to the dialed number, or the IVRU may send a SIP REDIRECT orsimilar message as above seeking to set up a call to the dialed number,without involving IP PBX server 50. An analogous process could becarried out to enable a WCD user to selectively apply cellular-PBXintegration, rather than selectively bypassing cellular-PBX integration.

c. Example Process Flow

FIG. 10 is a flow chart depicting an example set of functions that canbe carried out to provide for temporary bypass or application ofcellular-PBX integration service. As shown in FIG. 10, at step 336, aRAN serving the WCD receives a call request for the WCD, the callrequest including a directive of whether or not to apply cellular-PBXintegration service for the call. At step 338, a first leg of the callis requested to be set up between the RAN and a media gateway system,and call setup signaling is sent from the media gateway system to aCSCF.

At step 340, the directive is used as a basis to determine whether theWCD is currently checked-into or checked-out of the cellular-PBXintegration service. For instance, if the directive is to applycellular-PBX integration, then the determination may be that the WCD isconsidered checked-into the cellular-PBX integration service (e.g., evenif just for the present call), and if the directive is to not applycellular-PBX integration, then the determination may be that the WCD isconsidered checked-out of the cellular-PBX integration service (e.g.,even if just for the present call).

If the determination is that the WCD is checked-in, then, at step 342,the call setup signaling is passed from the CSCF to an IP PBX serverthat serves the WCD, to request set up of a second leg of the call fromthe media gateway system to the IP PBX server. On the other hand, if thedetermination is that the WCD is currently checked-out, then, at step344, then signaling is passed back from the CSCF to the media gatewaysystem to request setup of the call back from the media gateway systemto the RAN.

9. Location-Based Restriction on Cellular-PBX Integration

As explained above, integrating cellular telephone service with IP PBXservice will advantageously enable a WCD user to enjoy numerous IP PBXfeatures, such as the ability to place and receive PBX extension-dialedcalls, and the ability to place outside calls through the IP PBX server(e.g., using the enterprise's PSTN service provider), for instance.

For various reasons, however, it may be desirable to limit the locationswhere cellular-PBX integration can apply. For example, it may bedesirable to limit cellular-PBX integration to apply only when the WCDis in one or more specified locations or only when the WCD is not in oneor more specified locations. To reduce the burden on the IP PBX systemand the enterprise network, for instance, an enterprise IP PBXadministrator may wish to prevent a WCD from using of cellular-PBXintegration service when the WCD is in located anywhere other than adesignated “home” area.

To account for this desire, logic can be added to restrict applicationof cellular-PBX service based on the location of the WCD. Two exampleembodiments for carrying out this function are described in thefollowing subsections.

a. SCP-Based Location Restriction

In a first embodiment, the WCD's profile at the SCP 32 will indicate oneor more location-based restrictions for application of cellular-PBXintegration service. Generally, speaking, the location-basedrestrictions may define one or more location “zones” in whichcellular-PBX integration service is to apply or is not to apply. Eachsuch zone can be defined in various ways, examples of which include (i)geographic polygons, with nodes defined as latitude/longitudecoordinates, (ii) cellular coverage areas, such as sectors, cells, orMSC serving areas, for instance, or (iii) political zones, such asstreets, counties, cities or states, for instance. Other examples arepossible as well.

In practice, when MSC 22 is faced with a request to connect a call to orfrom WCD 14, MSC 22 will signal to SCP 32 in a conventional manner. SCP32 will then query the WCD's service profile record and therebydetermine that the WCD subscribes to cellular-PBX integration serviceand that the service is location-restricted. In response, SCP 32 willdetermine the current location of the WCD.

The SCP can determine the current location of the WCD in various ways,depending for instance on the zone definitions that define therestriction at issue. By way of example, if the zone restriction iskeyed to one or more MSC coverage areas, the SCP can determine the WCD'scurrent MSC serving area based simply on which MSC signaled to the SCP,as indicated by a point-code or MSC-ID carried in the signaling messagefor instance. As another example, if a more granular location isrequired, the SCP could send a position-determination request via STP 26to MPC 40, seeking a granular reading of the WCD's current location.Applying well known techniques, the MPC may then determine the WCD'slocation and report the location in a response message to the SCP. TheSCP, MPC, or some other entity can further apply mapping data to converta determined location into some other form, such as by convertinggeographic coordinates to a street address, city, or the like.

Provided with the location of the WCD, the SCP may then programmaticallydetermine, based on the location and the location-restrictions definedby the WCD's profile (or generally applicable location-restrictionlogic), whether the call should be handled as a cellular-PBX integrationcall or not. For instance, if the WCD is located in an area where theprofile logic indicates cellular-PBX integration service should apply,then the SCP would determine that cellular-PBX integration serviceshould apply for the current call. Whereas, if the WCD is located in anarea where the profile logic indicates cellular-PBS integration serviceshould not apply, then the SCP would determine that cellular-PBXintegration should not apply for the current call.

If the SCP thereby determines that cellular-PBX integration shouldapply, the SCP may instruct the MSC to set up the call to media gatewaysystem 74, and processing would continue as described above. On theother hand, if the SCP determines that cellular-PBX integration shouldnot apply, the SCP may instruct the MSC to handle the call as aconventional cellular call.

a. CSCF/HSS-Based Location Restriction

In another embodiment, the decision of whether to apply cellular-PBXintegration can be made by the CSCF or by an associated location policyserver 96. In this embodiment, the WCD's profile at HSS 82 will indicateone or more location-based restrictions for application of cellular-PBXintegration service, defined in the manner described above for instance.

When CSCF 76 receives a SIP INVITE indicative of a call being placed toor from WCD in any of the scenarios described above for instance, theCSCF 76 will dip into HSS 82 and determine from the WCD's profile that alocation-based restriction exists on application of cellular-PBXintegration service. Further, the CSCF may thereby ascertain a domainname of location policy server 96, such as “location-policy.com”. TheCSCF may then responsively send the INVITE or a corresponding message tolocation policy server 96.

Upon receipt of the INVITE, the location policy server 96 may thenitself dip into HSS 82 and thereby determine the applicablelocation-restrictions, such as the one or more zones in whichcellular-PBX integration service is to apply or is not to apply.Further, the location policy server 96 may determine the currentlocation of the WCD, by querying MPC 40 for instance.

The location policy server may thus programmatically determine, based onthe WCD's location and the location-restrictions defined by the WCD'sprofile (or generally applicable location-restriction logic), whetherthe call should be handled as a cellular-PBX integration call or not.For instance, if the WCD is located in an area where the profile logicindicates cellular-PBX integration service should apply, then thelocation policy server 96 would determine that cellular-PBX integrationservice should apply for the current call. Whereas, if the WCD islocated in an area where the profile logic indicates cellular-PBSintegration service should not apply, then the location policy server 96would determine that cellular-PBX integration should not apply for thecurrent call.

If the location policy server 96 thereby determines that cellular-PBXintegration should apply, the location policy server may signal back tothe CSCF 76 to cause the CSCF to apply cellular-PBX integration. On theother hand, if the location policy server 96 determines thatcellular-PBX integration should not apply, the location policy servermay signal back to the CSCF 76 to cause the CSCF to not applycellular-PBX integration. The function of applying or not applyingcellular PBX integration can be carried out in the same manner asdescribed above with respect to the check-in/check-out policy logic.

c. Example Process Flow

FIG. 11 is a flow chart depicting an example set of functions that canbe carried out to provide for location-based restriction on applicationof cellular-PBX integration service. As shown in FIG. 11, at step 346, aRAN serving the WCD receives a call request for the WCD. At step 348, afirst leg of the call is requested to be set up between the RAN and amedia gateway system, and call setup signaling is sent from the mediagateway system to a CSCF.

At step 350, a determination is made as to whether a location of the WCDsatisfies at least one condition. If the determination is that thelocation of the WCD satisfies the at least one condition, then, at step352, the call setup signaling is passed from the CSCF to an IP PBXserver that serves the WCD, to request set up of a second leg of thecall from the media gateway system to the IP PBX server. On the otherhand, if the determination is that the location of the WCD does notsatisfy the at least one condition, then at step 354, then signaling ispassed back from the CSCF to the media gateway system to request setupof the call back from the media gateway system to the RAN.

10. Account Balance Restriction on Cellular-PBX Integration

For perhaps the same reasons that an enterprise might want to restrictapplication of cellular-PBX integration based on location, an enterprisemight also want to restrict application of cellular-PBX integrationbased on the extent of use. For instance, an enterprise administratormay want to preclude a WCD user from using the cellular-PBX integrationfunction more than a designated number of minutes per month. By the sametoken, a cellular carrier or other entity might want to restrict a WCD'suse of cellular-PBX integration based on the extent of use.

To account for this desire, “account-balance” logic can be added. Inparticular, a WCD may be allotted a designated quantity of cellular-PBXintegration service, possibly with a time restriction, such as per monthor other billing period. The balance of minutes of use for a given WCDmay then be decremented as the WCD uses the cellular-PBX integrationservice. And once the balance is exhausted, the WCD would be precludedfrom using further cellular-PBX integration service (e.g., during theapplicable period).

To provide this account balance logic in a preferred embodiment, theWCD's profile will be provisioned initially (or periodically) with anaccount balance specifying an allowed quantity of use, such as a numberof minutes of call time for instance. An entity that sits within thecall signaling path between the cellular carrier's RAN 12 and the IP PBXserver 50 will then decrement that account balance for the WCD as theWCD engages in cellular-PBX integration calls.

By way of example, the WCD's profile in HSS 82 can be provisioned with avalue that indicates a number of allowed minutes of use of cellular-PBXintegration service. Further, as shown in FIG. 4, an account-balancepolicy server 100 can be provided on network 90.

When CSCF 76 receives a SIP INVITE seeking to set up a call for WCD 14from MGC 80 to IP PBX 50 or a SIP INVITE seeking to set up a call forWCD 14 from IP PBX 50 to MGC 80, CSCF 76 may perform some or all of thefunctions described above to determine whether the cellular-PBXintegration service should be provided, such as whether the WCD iscurrently checked-into or checked-out of the cellular-PBX integrationservice.

Further, when CSCF 76 dips into the WCD's profile at HSS 82, the CSCF 76will determine that the WCD is subject to an account-balancerestriction, and the CSCF 76 may receive a domain name of accountbalance policy server 100, such as “account-balance-policy.com” Inresponse, the CSCF 76 will thus preferably forward the SIP INVITE to theaccount-balance policy server 100.

Upon receipt of the SIP INVITE, the account balance policy server 100may itself then dip into the WCD's HSS profile, to determine the currentaccount balance for the WCD, such as how many minutes of use the WCD hasleft. (Alternatively, the CSCF 76 could provide this information in aSIP header parameter to the account balance policy server whenforwarding the SIP INVITE to the server.) Based on the remainingbalance, the account-balance policy server 100 may then determinewhether the WCD has a sufficient balance to proceed with thecellular-PBX integration call that is being set up. For this purpose, abalance can be considered sufficient if it is non-zero or if itsurpasses some other designated threshold level (such as 5 minutes forinstance.)

If the account balance policy server 100 determines that the WCD doesnot have a sufficient remaining balance, the account balance policyserver 100 will send a response message back to CSCF 76 directing CSCF76 to not apply cellular-PBX integration. Processing would then occur asdescribed above (as when the PE policy server 94 determines that the WCDis not currently checked-into the system).

On the other hand, if the account balance policy server 100 determinesthat the WCD does have a sufficient balance, the account balance policyserver 100 would then forward the received SIP INVITE back to the CSCF76 for transmission in turn to the destination SIP entity. For example,if the SIP INVITE had originated at MGC 80 and passed to CSCF 76 andthen to account balance policy server 100, the INVITE could then passback to CSCF 76 and, from there, along to IP PBX server 50 for IP PBXhandling. As another example, if the SIP INVITE had originated at IP PBXserver 50 and passed to CSCF 76 and then to account balance policyserver 100, the INVITE could then pass back to CSCF 76 and, from there,along to MGC 80 for signaling in turn to MSC 22.

In this manner, the account balance policy server 100 will remain withinthe SIP signaling path for the call being set up. Additional SIPmessages used to set up the call, such as SIP 200 OK and SIP ACKmessages, would pass between the SIP endpoints (e.g., MGC 80 and IP PBXserver 50) through the account balance policy server 100. Thus, theaccount balance policy server would see when the call is fully set up,such as when a SIP ACK passes between the endpoints. Further, SIPmessages used to tear down the call, such as a SIP BYE message forinstance, would also pass through the account balance policy server 100,and so the account balance policy server would also see when the callends.

In accordance with the exemplary embodiment, as the call proceeds, theaccount balance policy server 100 will programmatically decrement theWCD's account balance. When the call ends, the account balance policyserver 100 may then write the WCD's new account balance into the WCD'sHSS profile record.

Further, if the WCD exhausts the balance during a call, the accountbalance policy server 100 can take a predefined action in response. Byway of example, the account balance policy server 100 can automaticallytear down the call, such as by sending a SIP BYE to one or more of theSIP endpoints. Alternatively or additionally, the account balance policyserver 100 can redirect the WCD to a balance refreshment platform (e.g.,IVRU) such as by sending a SIP REDIRECT to the SIP signaling initiator.As still another example, the account balance policy server 100 canallow the existing call to complete normally and can then bar initiationof a new call due to the exhausted balance. Other examples are possibleas well.

In an alternative embodiment, some or all of this account balance logiccan be provided by SCP 32, using WIN prepaid triggers for instance. Inparticular, the WCD's profile at SCP 32 can be provisioned with a valuethat indicates a number of allowed minutes of use of cellular-PBXintegration service. SCP 32 can then apply account balance logic todetermine whether to direct MSC 22 to connect a call to media gatewaysystem 74 in the first place and can decrement the account balance asthe call proceeds. When the call ends, MSC 22 can then signal to theSCP, and the SCP can stop decrementing the WCD's account balance.

FIG. 12 is a flow chart depicting an example set of functions that canbe carried out to provide for account-balance based restriction onapplication of cellular-PBX integration service. As shown in FIG. 12, atstep 356, a quantity of cellular-PBX integration service is allotted toa WCD. At step 358, the quantity is decremented as the WCD uses thecellular-PBX integration service. And at step 360, the WCD is precludedfrom using the cellular-PBX integration service in response to thequantity being exhausted.

11. Differential Billing with Cellular-PBX Integration

In a typical cellular wireless communication system, a switch such asMSC 22 will generate a call detail record (CDR) for each call that ithandles, and the switch will send each CDR to a billing system, tofacilitate billing of the WCD account holder. The CDR typicallyidentifies the WCD that placed or received the call, the directorynumber of the other party, and the duration of the call, among otherinformation.

With cellular-PBX integration, another issue that arises is what entitythe cellular carrier should bill for such calls. On the one hand, thecellular carrier could bill the WCD account holder for a call. On theother hand, the cellular carrier could bill the WCD's associated IP PBXservice provider (enterprise) for a call.

In accordance with an exemplary embodiment, this issue can be resolvedby billing cellular-PBX integration calls to the IP PBX serviceprovider, and billing the WCD account holder (e.g., the WCD userpersonally) for non-cellular-PBX integration calls. (In some instances,the same entity might be the IP PBX service provider (enterprise) andthe WCD account holder; this exemplary embodiment can be applied even inthat instance, to facilitate separate accounting for the two types ofcalls.)

One way to do this in practice is to have SCP 32 provide a differentialbilling indicator in the intelligent network response message that itsends to the MSC 22 during call origination or termination. Forinstance, in an “orreq_rr” response message that the SCP sends back tothe MSC during call origination, the SCP may include (in auser-definable field or in some other MSC-discernable manner) a“personal” billing-indicator indicating that the WCD account holdershould be billed for the call or an “enterprise” billing indicatorindicating that the IP PBX service provider should be billed for thecall.

More particularly, when the SCP is directing the MSC to set up the callto media gateway system 74, the SCP can include an “enterprise”billing-indicator, whereas, when the SCP is directing the MSC to set upthe call as a non-cellular-PBX integration call, the SCP can include a“cellular” billing-indicator. Alternatively, the MSC can be programmedto treat a directive to set up the call to media gateway system 74 as anindication that the call is to be billed to one party (the enterprise)and a directive to set up the call conventionally as an indication thatthe call is to billed to another party (the WCD account holder).

The MSC 22 may then programmatically include in the CDR that itgenerates for the call a corresponding “personal” or “enterprise”billing indicator (in any predefined form). In turn, a billing systemthat receives the CDR may record the call in the appropriate account, soas to bill the IP PBX service provider for cellular-PBX integrationcalls and the WCD account holder for other calls.

FIG. 13 is a flow chart depicting an example set of functions that canbe carried out to provide for differential billing with cellular-PBXintegration service. As shown in FIG. 13, at step 362, request to set upa call to or from a WCD is received. At step 364, a determination ismade as to whether the WCD is currently checked-into or checked-out ofcellular-PBX integration service. If the determination is that the WCDis currently checked-into cellular-PBX integration service, then at step366, the call is set up with cellular-PBX integration, and the call isbilled to an enterprise account. On the other hand, if the determinationis that the WCD is currently checked-out of cellular-PBX integrationservice, then, at step 368, the call is set up without cellular-PBXintegration, and the call is billed to a personal account.

12. Conclusion

Exemplary embodiments of the present invention have been describedabove. Those skilled in the art will understand, however, that changesand modifications may be made to these embodiments without departingfrom the true scope and spirit of the present invention, which isdefined by the claims.

For example, various functions described above as being carried out byCSCF 76 in conjunction with one or more policy servers could be carriedout by CSCF 76 alone, by MGC 80, or by one or more other entitiesinvolved with call setup and management. As another example, variousfunctions described above could be combined together or conducted inseries. For instance, the CSCF 76 can signal in series to multiplepolicy servers, in order to facilitate application of multiple policiesrelated to cellular-PBX integration for a given call. Similarly, the SCP32 can apply multiple polices related to cellular-PBX integration for agiven call.

As still another example, while the foregoing description uses the term“WCD” and discusses application of cellular-PBX integration service andconnection of calls for a WCD, it should be understood the a WCD cangenerally constitute a wireless subscriber, which can be a device and/ora user of the device. Thus, a policy or state can be set or applied fora given user's WCD by setting or applying the policy or state for thegiven user, and a policy or state can be set or applied for a given userby setting or applying the policy or state for the given user's WCD.Other examples are possible as well.

1. A method comprising: receiving into a cellular radio access network(RAN) a call request seeking to set up a call for a cellular wirelesscommunication device (WCD) that is operating in a wireless coverage areaof the RAN, wherein the call is a call to a called party; responsivelymaking a determination of whether the WCD is currently checked-into acellular-PBX integration service to which the WCD subscribes; if thedetermination is that the WCD is currently checked-into the cellular-PBXintegration service, then setting up the call to an IP PBX server thatserves the WCD; and if the determination is that the WCD is notcurrently checked-into the cellular-PBX integration service, thensetting up the call to the called party without setting up the call tothe IP PBX server, the method further comprising maintaining asubscriber profile record for the WCD, wherein the subscriber profilerecord includes an indication of whether the WCD is currentlychecked-into or checked-out of the cellular-PBX integration service,wherein making the determination of whether the WCD is currentlychecked-into the cellular-PBX integration service comprises referring tothe subscriber profile record to determine whether the WCD is currentlychecked-into or checked-out of the cellular PBX integration service. 2.The method of claim 1, further comprising: after setting up the call tothe IP PBX server, setting up the call from the IP PBX server for theWCD.
 3. The method of claim 2, wherein the call is a call to the WCD,and wherein setting up the call from the IP PBX server for the WCDcomprises performing a function selected from the group consisting of(i) ringing the WCD, (ii) simultaneously or sequentially ringing the WCDand a designated IP PBX extension, and (iii) sending the call to a voicemail box associated with the IP PBX server.
 4. The method of claim 2,wherein the IP PBX server includes data that associates an IP PBXextension number with the WCD, wherein the call is a call to theextension number, and wherein setting up the call from the IP PBX serverfor the WCD comprises performing a function selected from the groupconsisting of (i) ringing the WCD, (ii) simultaneously or sequentiallyringing the WCD and a designated IP PBX extension, and (iii) sending thecall to a voice mail box associated with the IP PBX server.
 5. Themethod of claim 2, wherein the call is dialed from the WCD to a callednumber, and wherein setting up the call from the IP PBX server for theWCD comprises setting up the call from the IP PBX server to the callednumber.
 6. The method of claims 5, wherein the called number is adirectory number, and wherein setting up the call from the IP PBX serverto the called number comprises setting up the call from the IP PBXserver over the public switched telephone network to the directorynumber.
 7. The method of claim 5, wherein the called number is an IP PBXextension number, and wherein setting up the call from the IP PBX serverto the called number comprises setting up the call from the IP PBXserver to an IP PBX extension phone having the IP PBX extension number.8. The method of claim 1, wherein the cellular RAN includes a basestation that radiates to define the wireless coverage area and a mobileswitching center (MSC) that is communicatively linked with the basestation, wherein the MSC is further communicatively linked with aservice control point (SCP) to which the MSC signals for call processingguidance in response to the call request, and wherein: making thedetermination of whether the WCD is currently checked-into thecellular-PBX integration service comprises the SCP determining whetherthe WCD is currently checked-into the cellular-PBX integration service,and setting up the call to the IP PBX server that serves the WCDcomprises the SCP instructing the MSC to set up the call to a mediagateway system for connection of the call thereafter from the mediagateway system to the IP PBX server.
 9. The method of claim 8, whereinmaintaining a subscriber profile record for the WCD comprisesmaintaining the subscriber profile record at the SCP, and whereinreferring to the subscriber profile record comprises the SCP referringto the profile record.
 10. The method of claim 8, further comprising:receiving, from a user, a provisioning instruction to check the WCD intoor out of the cellular-PBX integration service; and responsivelyprovisioning the profile record to accordingly indicate whether the WCDis currently checked-into or checked-out of the cellular PBX integrationservice.
 11. The method of claim 10, wherein receiving the provisioninginstruction from the user comprises receiving the provisioninginstruction through a web-based provisioning interface or receiving theprovisioning instruction as a feature-code provisioning instruction. 12.The method of claim 1, wherein the WCD operates under a WCDbilling-account, and wherein the IP PBX server operates under anenterprise billing-account, the method further comprising: if thedetermination is that the WCD is currently checked-into the cellular-PBXintegration service, then charging the call to the enterprisebilling-account; and if the determination is that the WCD is currentlynot checked-into the cellular-PBX integration service, then charging thecall to the WCD billing-account.
 13. The method of claim 12, wherein thecellular RAN includes a base station that radiates to define thewireless coverage area and a mobile switching center (MSC) that iscommunicatively linked with the base station, wherein the MSC is furthercommunicatively linked with a service control point (SCP) to which theMSC signals for call processing guidance in response to the callrequest, and wherein: making the determination of whether the WCD iscurrently checked-into the cellular-PBX integration service comprisesthe SCP determining whether the WCD is currently checked-into thecellular-PBX integration service; charging the call to the enterprisebilling-account comprises the SCP including an enterprise-billingindicator in a directive that the SCP sends to the MSC; and charging thecall to the WCD billing-account comprises the SCP including aWCD-billing indicator in a directive that the SCP sends to the MSC. 14.The method of claim 1, further comprising: receiving together with thecall request a toggle command, wherein making the determinationcomprises (i) referring to the profile record to ascertain whether theWCD is currently checked-into or checked-out of the cellular-PBXintegration service, (ii) if the profile record indicates that the WCDis currently checked-into the cellular-PBX integration service, thendetermining in view of the toggle command that the WCD is currently notchecked-into the cellular-PBX integration service, and (iii) if theprofile record indicates that the WCD is currently checked-out of thecellular-PBX integration service, then determining in view of the togglecommand that the WCD is currently checked-into the cellular-PBXintegration service.
 15. The method of claim 14, wherein the togglecommand comprises a feature code.
 16. The method of claim 1, wherein thecall is a call between the WCD and a party other than the WCD, andwherein making the determination of whether the WCD is currentlychecked-into a cellular-PBX integration service to which the WCDsubscribes comprises basing the determination at least in part on anidentity of the party other than the WCD.
 17. A method comprising:receiving into a cellular radio access network (RAN) a call requestseeking to set up a call for a cellular wireless communication device(WCD) that is operating in a wireless coverage area of the RAN, whereinthe call is a call to a called party; receiving together with the callrequest a directive of whether or not to apply cellular-PBX integrationservice for the call; responsively making a determination of whether theWCD is currently checked-into a cellular-PBX integration service towhich the WCD subscribes, wherein if the directive is to applycellular-PBX integration service for the call, then the determination isthat the WCD is checked into the cellular-PBX integration service, andif the directive is to not apply cellular-PBX integration service forthe call, then the determination is that the WCD is not currentlychecked-into the cellular-PBX integration service; if the determinationis that the WCD is currently checked-into the cellular-PBX integrationservice, then setting up the call to an IP PBX server that serves theWCD; and if the determination is that the WCD is not currentlychecked-into the cellular-PBX integration service, then setting up thecall to the called party without setting up the call to the IP PBXserver.
 18. The method of claim 17, wherein the directive comprises afeature code.
 19. A system comprising: a cellular radio access network(RAN) comprising a base station that radiates to produce a wirelesscoverage area; subscriber profile data indicating whether a cellularwireless communication device (WCD) is currently checked-into orchecked-out of a cellular-PBX integration service to which the WCDsubscribes; a media gateway system; a call session control function(CSCF) arranged to engage in signaling communication with the mediagateway system; and an IP PBX server arranged to serve a plurality ofenterprise telephone stations that are situated on an enterprisepacket-switched network, the IP PBX server being further arranged toengage in signaling communication with the CSCF and bearer communicationwith the media gateway system, wherein the RAN receives a request to setup a call for the WCD when the WCD is operating in the wireless coveragearea and, responsive to the profile data indicating that WCD iscurrently checked-into the cellular-PBX integration service, the RANsets up the call to the media gateway system for connection of the callin turn to the IP PBX server.